I purchased one. Probably the best new product I've used in many, many years. I was interested in it, sure, but was not planning on purchasing it. Once I got my hands on one, though...couldn't resist!
Sure, Office is still a preview version, but Microsoft will be giving you the full version for free when it's released! That's really awesome of them, and I love that I can use the tablet for work if needed. I'm glad they went ahead and included the preview version instead of waiting, and they do notify you when you open the application that it is a preview version and that it will eventually update to the RTM version for free.
The touch keyboard works surprisingly well, and I'm a touch typist that's used to a mechanical keyboard. I only find it problematic when trying to enter passwords, as I'm not quite up to par on it without seeing what I'm typing in real-time.
Some of the apps take a bit to load, but I'm sure that will be ironed out over time. Either way, the tablet doesn't FEEL slow. Plus, once you have something open, multitasking is extremely easy.
The low resolution screen is a non-issue. Sure, you can tell it's not as high resolution as the iPad, but it's still a fantastic looking screen. Touch works perfectly.
Speaking of touch, it does take a bit of time to learn your way around the OS. A lot of the touch gestures and operations are different than what you'd expect if coming from iOS or Android. But, once you get used to them, they work really, really well! It's actually quite enjoyable to use. Sometimes it's a bit tricky navigating around in the desktop mode with touch, but it works well enough. If you have the touch cover, it's a non-issue thanks to the tiny track pad.
I haven't encountered any issues related to bugs or stability.
The more and more I use Windows 8, the more I like it. Sure, it does at times feel like it's a split personality OS that has some integration issues, but I find these concerns disappearing as I become more acclimated with the environment.
On my PC, I primarily use the desktop environment. It works perfectly well, and I have no issues using the start screen instead of the start menu. Works the same in the end. On my Surface, I primarily use the Modern UI. However, I can switch to the desktop mode if need be, and that also works just great! The more you use it, the more you appreciate that you have the exact same OS running on multiple devices...and they all work perfectly well!
The only REAL complaint I can offer about Surface is the app selection. But, what do you expect? I have some worries that the ARM development won't pick up as well as it should, but it's already picking up fairly quickly. For now, it's a pretty poor tablet as far as having many high quality apps available goes, but that should hopefully change quickly. Once it does...I think Windows 8 has the potential to take over the market. Maybe.
Long story short, Surface is way better than I expected it to be. Once you use it and Windows 8 across multiple devices for a while, you'll probably feel the same way.