I decided to make the plunge and get a PSP in January. If the current bundles are still available, it will be difficult to choose between the God of War bundle and the Ratchet and Clank bundle. The GoW one interests me more because I love GoW and think that the red PSP is gorgeous, but the R&C one has a 1GB memory card and a downloadable game (not to mention National Treasure 2), so it's a better value for the same price.
I guess that nonetheless, my choice will be thus: GoW first, Ratchet second (if the GoW bundle is no longer available anywhere).
If anyone wonders why go for the PSP when I have a DS and an iPod for movies, well, it's simple. There's one genre sorely lacking on the DS, and it's hack-and-slash. Another advantage to having 2 portable consoles is that Eric could play one while I play the other when we're on the go -- it's not fun to watch someone else play videogames all the time (granted we could do that with the GBA SP...).