Even tho somethings like Move never lived up to potential. I have to say the worst is UMD. In theory, I understand the concept, but they allowed you to use Sony memory sticks and supported video formats from the moment you started using the PSP. So out of the gate, PSP UMDs were useless. Not to mention, this is a device in your pocket. People don't bring a bunch of movies with them on the Go, and if it's between a game and a movie, carrying a PSP is going to be a game. It was a case of just because you can, does not mean you should. Sony was still in that era of trying to force new physical media formats and failing. Blu-ray is the only one they ever succeeded at. PSP should have used cards like DS.
The funny thing is. When Nintendo used carts for N64 they sealed their fate. Fortunes reversed with DS and PSP. Using discs sealed PSPs. Yes, it still sold well. Still got spanked by DS. A lot of other Sony stuff was maybe a good idea but never used well. UMD's were a bad idea, period.
Bite my shiny metal cockpit!









