I also didn't much care for the Marion & Luigi set of RPGs. I only played the DS one, and I thought it was kinda boring, both in gameplay and story-wise. I tried to stick it out to the end, but after getting thru about 80% finished, I finally just decided to be done with it. I gave it to my 10-yr old nephew, who loved it.
And I also still don't care much for the "rock-star" prosecutor. Although you do find out alot more about him and he has a very key role to play in the game, he still is no Edgeworth. I'm neck-deep in Case 4, and I do like the little twist they've thrown in.