I am currently using VS2010 Premium, and have heard that the debugging in Ultimate is so much better. Is it really worth upgrading to Ultimate to take advantage of the new debugging features they've included? Or is it marketing hype and not really usable for every day development scenarios?
I believe the feature is called IntelliTrace.
Do you work in a team? Do you get bugs reported to you by a tester, and then you can't repro them? Would it save you a lot of time to be able to "debug" through the actual setup the tester had - see their values and execution path? Or perhaps you work with another developer. Would you like to be able to set a bunch of breakpoints and leave "notes" in the code (pinned data tips) and then export them and give them to the other developer, saying "the bug we're looking for is in your part of the code".
If those scenarios cause you pain now, you want Ultimate. If you work alone, it's possible that IntelliTrace alone will make you want Ultimate. It is cool to "time travel" in the debugger.