Man, I love Keynote--it's a great program, but I had to do some layout work with Pages and boy was it a doozy on my system. Even though it was just basic text and tables it was still very sluggish and unmanageable.
I wouldn't pay more than $50 for that program though, that's for sure.
Yeah, like ldburroughs said...iWork costs the same or less than Keynote did before. Seems like an awkward thing to complain about. You can always not install it. When I bought iLife 05, the only app I've installed so far is iPhoto 5.