It's fair to say that if you found either of the previous two PSP outings enjoyable then FM Handheld 2008 is unlikely to disappoint. It's unlikely to bowl you over with new features or improved AI, and it's certainly not going to convert anybody that found the previous handheld versions too watered down.
But if you really must have the latest squads or feel that any of the new features are just what you were missing last time around then, despite the awful transfer system and lacklustre commentary, FM Handheld 2008 could be money well spent.