Just like it's DS counterpart, the PSP version has also been very highly rated by critics. It is currently Gamespot's highest rated PSP game of all time. It's 9.5/10 rating surpasses that of both Liberty City Stories (8.6) and Vice City Stories (8.4) - so if you were a fan of those, you're sure to love Chinatown Wars.
Gamespot didn't really have that much to say of any flaws, apart from the fact some of the DS minigames don't play as well on the PSP (which we expected), and some camera issues.
"At first glance, Chinatown Wars could be mistaken for a return to the Grand Theft Auto series' humble 2D beginnings. The action is viewed from a more or less top-down perspective, and of course you still spend much of your time driving stolen cars and causing trouble with firearms. But the similarities between this superb PSP game and its '90s progenitors pretty much end there. Chinatown Wars actually has more in common with GTAs III and IV than it does with earlier games, and, remarkably, it even adds to and improves on the formula that made those games so successful. That's a bold statement for sure, but Chinatown Wars really is that good... It's also one of the best GTA games yet."
Link: GTA Chinatown Wars PSP review