Medal of Honor: Heroes does not live up to the franchise in any aspect, but still is a decent buy for your PSP.
GRAPHICS: Character models and animations are decent, not great. Environments look good but textures are bland and un-detailed. This game could've done better.
GAMEPLAY: Very repetitive and occassionally boring. There is no stealth or vehicle segments. When you start a mission, enemies come after you right away. All you have to do is capture areas or blow up certain things. Not very innovative. However, the assortment of guns and the extreme replayability value (boosting your rank, getting all gold medals, unlocking awards and uniforms) helps repair the damages. Skirmish mode is also another neat addition. It is basically you versus COM players. In Skirmish mode you don't unlock anything, but you can set yourself a record to beat and it gives you extra play time.
AUDIO/SOUNDTRACK: A nice, catchy menu theme that fits WWII perfectly. Everything sounds decent, from guns to voiceacting. Not amazing, but also not horrible either.
ONLINE: Haven't tried it, but I assume nobody plays it since it was made in 2006 and already has a sequel.
VALUE: Buy if you need an FPS or if it is under $15. Otherwise, search for a different game.
OVERALL
Pros: Lots of stuff to unlock, nice environments, good assortment of guns, good menu theme, Skirmish mode
Cons: Nothing special, no vehicles, poor textures and character models, extremely short campaign