I use MS Office at work, and iWork on my personal computer (which also gets used for work frequently).
For the price, iWork is a much better suite than MS Office .... for the price. Which is why I bought iWork in the first place, because MS was charging four times as much for the essentially the same functionality.
I love Keynote... and it does blow Powerpoint out of the water. Pages and Numbers work fine, but they are different than their MS equivalents. If you are used to MS, you might be frustrated with iWork at first, but I have found how to do everything in iWork that I did in MS.
However.... if you are needing full compatibility between your office and home computers, research iWork carefully before purchasing and make sure it isn't going to cause you problems. For example, converting a gorgeous Keynote presentation to MS does not work well because MS cannot handle some of the cool things that Keynote does. I have had to export my Keynote presentations as Quicktime, instead of a straight Keynote-to-Powerpoint export, to get them to play on PCs the way I laid them out on the Mac.
If I could only have one, I'd choose iWork. It's inexpensive and it does what it says..... work, and very well at that.