Though Apple is a littlelate to the 2-in-1 party, playing the role of follower, that doesn't mean the iPad Pro can't still play a key role in the long term. Butwhat about for you – right now? Is the iPad Pro 9.7 worth considering as a Surface Pro 4alternative? These are two very different devices with a little overlap,and a lot of lopsided use cases.
Size

Apple's larger 12.9-inch iPad Pro is more of a direct rival to the Surface Pro 4 than this 9.7-inch model is. This one lookspretty small compared to the Surface – in landscape mode Microsoft's 2-in-1 is18 percent taller and 22 percent wider.
If you mostly want a classic tablet, and see things like a keyboard and stylus as more of a bonus for the occasional email, spreadsheet or word processing doc, then that fits the iPad Pro 9.7 to a T. For more serious productivity, the iPad Pro series doesn't (yet) stack up.
Weight

The smaller (Wi-Fionly) iPad Pro is 43 or 44 percent lighter than the Surface Pro 4.
Build

You get a premium,all-metal build from either tablet.
Keyboard cover

Both tablets'keyboard accessories are sold separately. The Surface's Type Cover is moreadvanced, with a glass trackpad (more on that next), but Apple's stock keyboard costs US$19 more.
There are alsothird-party keyboards you can use with the iPad Pro, but we think Apple's is overpriced for its limited capabilities (read on).
Trackpad

It's hard for us to call the iPad Pro a laptop when it doesn't have a trackpad – or pointer support of any kind beyond its stylus. It's more of a faux-book, where you have to constantly reach up to swipe and tap the screen vs. just sliding your fingers a few centimeters below the keys.
It will beinteresting to see if Apple adds mouse/trackpad input to iOS in the next yearor two. Though we aren't going to hold our breath, it's also hard to see the Pro series ever living up to its name with touch-only software. Often old-school features and ideas are hanging around only because of our collective habits, but when it comes to productivity we could make a long list of good reasons why mouse/trackpad control isn't ready to die.
Backlit keyboard

Some of the iPadPro's third-party keyboards have backlit keys (at least in the larger model), but not Apple's own.
Adjustable screen angle in laptop mode

If you're using Apple's official Smart Keyboard for the iPad Pro, then you won't be able to adjust the screen angle. I find the fixed position to be too vertical in lap – and if you're in a reclined position the iPad might topple over on top of the keys.
Stylus

Keep this in mindwhen you look at total cost, as the excellent Surface Pen is bundled with theSurface Pro 4. The Apple Pencil is a separate $99 purchase.
Handwriting recognition

When you're using the Surface as a pen-based tablet, you can use the Pen to scribble out some chicken scratch, which Windows will (capably) translate into text. iOS doesn't have built-in handwriting recognition – you'll be using either a physical keyboard or a virtual keyboard.
Colors

You have four coloroptions to choose from with the iPad, while the Surface itself only ships in one black front/silver back option.
You can add some personal flair to theSurface, though, with different-colored keyboards. Apple's keyboard only ships inone dark gray option.
Display size

The 12.9-inch iPad Prohas a bigger screen than the Surface Pro 4, but this iPad's screen is only65 percent as big (as always, we measure that based on area, not diagonal).
Display resolution

Pixel densities arevery close – and both screens look terrific. Nothing to worry about here.
True Tone display

Apple's screen has anew feature that uses sensors to automatically adjust its white balance basedon your ambient environment. This isn't an upgrade-worthy feature, though, more like aneat bonus if you're already buying the iPad Pro 9.7 for other reasons.
Display type

Both tablets haveIPS displays.
Facial recognition login

The Surface's Windows Hello lets you log in just by flashing your pretty mug to the camera.
Fingerprint sensor

Like all modern iOS devices, the iPad Pro 9.7 has a Touch ID fingerprint sensor home button.
The Surface doesn't have a fingerprint sensor on the tablet itself (for most people it's redundant due to the facial login), but you can buy a $30 more expensive Surface keyboard cover that does a fingerprint sensor. That option is more for the backwards-compatible Surface Pro 3, which doesn't support facial login.
Cellular option

There has yet to be a Surface Pro with cellular capabilities.
USB

Apple wants iOS devices (and now Macs) to be as port-minimal as possible, using wireless instead.
If you have a DSLR or other camera that doesn't have built-in wireless (since we're talking "Pro" here, Apple), then you'll need to buy an adapter for the iPad – and also know that the App Store's mobile version of Lightroom won't directly support RAW images from your camera.
Battery

In our battery test,the Surface Pro 4 (somewhat surprisingly) had the slightly betterresult, dropping just 9 percent per hour for the Core i5 model and 11 percentper hour for the Core M model. The iPad dropped 12 percent per hour in the sametest.
Camera megapixels

We think it'soverkill for a tablet – especially if it's contributing to the new iPad's price hike over its predecessors – but the new iPad Pro has thesame rear camera as the iPhone 6s.
Processor

Despite using mobile architecture, the iPad Pro's A9X chip is an absolute beast, withdesktop-class performance (as does the Surface Pro, of course).
Just don't make themistake of thinking desktop-class performance was the only thing the iPad needed to offer desktop-class productivity. See also: lack of trackpad, lack of filesystem access, lack of desktop software and sandboxed (confined/limited/hard to transfer content from)apps. These things aren't a problem if you're just using the iPad as a casual tablet, but if you're talking about replacing your laptop with it, they matter.
Fanless

One big advantage of mobile processors like the iPad's A9X is that they're completely fanless. Only the Surface's somewhat underpowered entry-level model is fanless.
RAM

The iPad's 2 GB of RAM ishalf what its big (12.9-inch) brother has. It's also half the amount in theentry-level Surfaces – though mobile-based iOS can get by with less RAM thandesktop-based Windows can.
Storage

One way of looking at this is 32 GB storage is double the entry-level tier on any previous 9.7-inch iPad. The other way of looking at it is 32 GB is something of a joke for storage on a "pro" level device that you use a laptop.
This ties into the broader theme with the iPad Pro series: right now it's only "Pro" in name – planting seeds for the future in customers' (and developers') imaginations.
MicroSD

The iPad's built-in memory is the beginning and end of its storage story. You can pop a microSD into the Surface to expand its available storage.
Software

It's iOS 9 vs. Windows 10, which means you get better tablet-first apps from the iPad and much better laptop/productivity apps and functionality on the Surface.
One of the Surface's few weaknesses is its selection of tablet-first apps in the Windows Store. It's far behind the iPad App Store's selection – and many of the Windows Store apps that are there haven't been updated since the Windows 8 days. We aren't making too much of a stink over this, though, because there's such an abundance of desktop and web-based software that can fill the same roles (and works well enough in tablet mode) – in addition to its far superior productivity.
Release

The iPad Pro 9.7 just launched, about five months after the latest Surfaces.
Starting price

This smaller iPad Pro starts at $300 cheaper than the Surface Pro 4, but remember that the Surface Pen is included in the box while the Apple Pencil is a separate $99 purchase. The total starting price of tablet/keyboard/stylus for the iPad is $847, while the same combo for the Surface starts at $1,029.
... and if you're curious about the bigger iPad Pro (not included in this comparison), its starting price for tablet + accessories is $1,067.
For more on these two, you can hit up our reviews of the iPad Pro 9.7 and Surface Pro 4.