Hi,
Yeah it'll work fine with games released over here as the game side of the system is completely region free.
If you plan on watching movies though, you'll have to go with a JAP system, due to the fact that UMD Media are going to be region locked.
Also, there are rumours that the JAP PSP use a better quality Sharp TFT Display than that of the US systems Samsung displays. It is also reported that the JAP units have longer range Wi-fi but as I say, I don't know how accurate that last point is.
One thing to note though, is that on a Poll on the Lik-Sang forums, the newer JAP 2005 produced units have much lower pixel defect rates, whilst the US consoles still seem to be 50/50. I have a newer JAP - and sure enough - no dead pixels.
Hope that sort of helps you...