well, I think that anyone loyal to either of the following series' was dissapointed by their PSP games; Ratchet and Clank and Jak and Daxter.
Size Matters was OK, but was really glitchy, was prone to file corruption and had some frustratingly difficult or tedious sections.
Secret Agent Clank however was an improvement, but had stupidly long loading times, and some more tedious sections, such as the prison arenas, as well as a challenge mode that was un-beatable.
J&D the lost frontier was the worst game I know of. I only ever played the demo and that was enough to make me decide to never even touch the box for that game, for the first time in the Jak series, there were actually loading screens, there was no roll/crouch which meant no long or high jumps, there wasn't even a day/night cycle, and the scripting for that game was so terrible!
Daxter, was, like SAC, a massive improvement. But then again, Daxter was made by Ready At Dawn studios instead of High Impact. So, it still wasn't as good as a Naughty Dog Jak title, but personally I think Daxter is one of the best PSP games available, graphics that look good even when they're blown up, and no glitches to speak of!
But my point is that Size Matters and Lost Frontier have got to be the games I hate most.