I think it will do better than some people give it credit, but not as well as some of us would like. The RT tablet will be a great competitor, I think, with the current crop of tablets, especially once MS gets more developers on board. Of course, until they do, it's not as strong of a competitor, especially at its current pricing scheme. It has some big names behind it (Netflix, Pandora, Box.net, Amazon, to name a few), but not enough.
The Pro tablet, on the other hand, should blow them out of the way for people trying to be productive. The Pro tablet will not only be for consumption, and I think that's a strong selling point. I have, for years, wished I could use my tablet to write apps so that I don't have to bring a big laptop everywhere with me just to crank out some code. There are some Java IDEs for Android that are finally cropping up, but for most of my business software, I'm writing in .NET, which requires Windows. And, because it'll run all the same apps as the RT version, it will still have its consumption capabilities (ereading, movies, etc). Corporations and enterprises will also have a good reason to start using them for when employees go on business trips in order to keep all documents synced with the office AND seamlessly work with all Microsoft services they already have in place, like Sharepoint and Outlook servers.
I just can't figure out why they aren't releasing the Surface Pro with the RT?
(seriously, I'm not trying to anger anyone, these are really my views, coming from an Android user/developer since the OG Droid was released)