If the campaign was longer than roughly 90 minutes, MOH: Heroes could've lived up to some serious potential.
Most of the missions can be completed quickly, which makes it an ideal game for a quick burst of fun on a bus ride, and the visual and audio aesthetics are solid. The controls are a little bit awkward, but that's to be expected for an FPS on the PSP - the developers clearly did the best they could with the system's layout, though, so this is a minor gripe. My biggest issue with Medal of Honor: Heroes is the brevity of the campaign; I beat the entire game in less than 90 minutes, and while I could play it more times to complete side-objectives, I don't think the game is quite good enough to justify playing it through more than once or twice. If I had payed full price for Medal of Honor: Heroes, I would've been very disappointed, but considering that it can easily be found for under $10 these days, this is worth picking up for fans of the series. While the game does very little to rise above 'average', Medal of Honor: Heroes is definitely a fun game that I enjoyed spending some time with.