A very good FPS for the PSP, but does have a few flaws.
I'll be honest, what makes Medal of Honor a must-have in your PSP collection is because of the online play, it's got very good online play with leaderboards, 32 players online, the lot. What makes it a little poor are the controls, the online cheaters and the poor storytelling in the single player mode.
The offline modes are pretty weak, you have your campaign and a mode named 'skirmish' which is like offline multiplayer with bots, but you're unable to change any options such as what gameplay mode you wish to play or the kill limit. The campaign is nothing to write home about, the map designs are those you can play in the multiplayer, and you basically run around aimlessly finding the next objective to complete and so and so until the message 'mission complete' appears. Your team-mates in the campaign are very annoying shouting random quotes, and the enemies are able to shoot you through walls...
No, this game isn't terrible, it is worth buying if you want to experience a decent FPS on the handheld PSP, but the multiplayer makes everything worth it. Despite the odd cheater who happens to run around with a shotgun at 900 miles per hour, he/she can be kicked if you're the host and there are some good modes to play.
So if you want to finally play a decent FPS on the PSP, it's right here.