I spent some time this weekend with a Surface Pro and here's what I think:
It's too goddamned heavy.
It's subjectively every bit as fast as my Thinkpad (which is 1.1GHz faster and has two extra cores) for everyday PC tasks like web browsing and Word Processing. Programs open, you can sort-of do work. Maybe it's better with the clicky keyboard, but I have the squishy one. I'm also not sure I could ever load the machine down enough to get a full idea of its capabilities; maybe if I had it plugged in to a second display and was using it more like a docked laptop. Right now I have Firefox, Access, VLC, Terminals, SQL Management Studio and Word open on it and everything is just dandy. The important take-away here is that it's plenty of computer for doing computing.
The screen is gorgeous. It is lust-inspiring, in fact.
Battery life is just OK for a Windows machine, around four hours. The real web is nice. But it's too heavy for me to want to hold it and use it in the way I use my Android tablets. Granted that I also think that ipads and 10" Android tablets are a bit unwieldy, but this is around 1lb. over that line.
I'm not sure I see a problem with not having craploads of local storage. I stuck a 15GB collection of demo files on it and of course all that stuff was fine, though I'm not fond of any e-Reading software for Windows. The Photos Metro app kind of makes some sense when you can actually use it with a touchscreen. However, just like an Android tablet, I found myself doing basically everything with network resources anyway; stuff got saved to Google Drive or Skydrive or one of the WebDAV folders in my apartment and all was well. I found that I could install programs perfectly well on an SD card, though at least with the Verbatim Class 10 64GB card I have, starting programs (Visio 2007, MSSMS - which is way awful on a touchscreen) were definitely not as snappy as on the internal SSD.
Printing was an is ridiculously easy. I took the thing to one of my computer labs and it found and installed drivers for four different kinds of printers and the networked copier without any intervention on my part. I just looked and they were THERE. Printing is absolutely a strength for Windows 8; I've only wanted to print something from Android maybe a half dozen times and I do have a tool to let me, but it's a hassle.
Since I was dealing with a tablet, complete with sucky keyboard and touch input that make cut/copy/paste obnoxious, something I did miss a lot was a functioning "Share" feature. Windows 8 does have a Share charm, but it doesn't do anything useful and I'm not sure it can be modified by anything or if it's just that developers aren't bothering to modify it because it IS useless. I missed being able to tap a URL or image or something and send it out as an Email or something. It's not THAT much work to add things to the Send To context menu in Windows, but web browsers and standard Windows programs just are not well optimized for touch input, leaving me in a confusing place where neither my normal workflow for Windows 8 (pretend the Metro screen does not exist) nor my normal workflow for Android were quite working. I might get used to it with a little time.
Some things I want to try on this device are OneNote and at least some gaming. I have a small collection of Bluetooth thingies and a mini-displayport adapter that I should be getting on or around Wednesday. They might drastically change my user experience, at least for a "home base" location.
Right now I think the Pro is just too heavy to use as a regular tablet. I think it could be a decent ultraportable computer, were that one's only option, but I'm almost positive it would be a cheaper and generally better experience to have an Android tablet and some kind of inexpensive ultrabook, if that's the sort of thing you need.