Even though I own one, I'm going to go with a solid NO, unless you can name at LEAST 5 exclusive games you really want that are either out, or will be out in the near future (like next 3 months)
If there really aren't 5 games you are interested in, then spending $400 just for so few games really isn't worth it.
However, you also need to consider how much you want a Blu-ray player too, as I got mine for $300, I wanted a blu-ray player, and I wanted like 4 titles that are out now, and I don't own a X360. So it was worth the $300 for me.