This IDE is open source, and looks almost identical to it's VS2005 brother. I've coded up an application and opened and edited in both and they seem to like each other's formats (.sln and .proj).
There are a few missing items, but overall a great tool. One of the biggest things is the intellisense. When you start typing a line you won't get any intellisense. Also, if you delete a '.' and then retype, you'll need to do it one more time before you'll get a list of sub-items like methods and what not.
Check it out though if you don't got the moola for VS2005. Definately cool stuff.