The iFixit folks have finally given the Surface Pro their signature teardown treatment. After painstakingly stripping the Windows 8 Pro tablet to its bare ribbon cables, they declared that it was ever so lightly less repairable than the iPad 4 (aka the "iPad" now) and a whole lot less repairable than the original Surface RT. The increased difficulty of repair seems to be mainly related to initially getting into the device and the unnecessary gluing of the battery to the chassis.
Unfortunately, the battery itself, was glued to the back panel and was lambasted by iFixit for being a completely unnecessary move. Although not impossible to replace it seems that Microsoft meant it to be replaced with the back panel. Likely because taking a heat-gun or poking at it to remove it probably isn't such a great idea if you don't know what you're doing at home. There is however a possibility of completely removing that battery and putting in a larger capacity unit down the road, directly addressing the low battery life issue.
In the end, we really can't be surprised by the difficulty of breaking into the Surface Pro. It was designed specifically to be as thin and light as possible with the guts of an Ultrabook inside. Unlike the iPad (or even the Surface RT in some aspects), there is much you can do once you do get in. Plus, where there is risk in DIY, there is reward and if you can get inside without breaking the screen, you'll be able to silence any storage pundits who criticize the usable storage (since clarified and mythbusted by Ed Bott) with the installation of a massive 480GB mSATA SSD. Just because you can.