I agree with all of this.
I've been playing platformers as one of my favorite genres for the better part of 30 years now, and IMO, LBP's controls aren't bad at all. I had no issue with running, jumping or direction change at all. The only "issue" I had was adapting to going "in and out" of the 2.5D environment reliably, but I figured it out and adapted to that pretty quickly.
I don't know if its a "it's not like Mario" thing with some players or not, but I know I had no issue with the way Sackboy jumps.
Your problem with finding the great levels was my greatest problem as well. Thankfully, NeoGAF came to the rescue with the LBP levels thread, but there really should be some better way of finding the quality levels in game. Hopefully, this will be addressed once and for all with LBP2, otherwise, I'm depending on GAF to tell me about the great levels again.
The only other issue I had with LBP was that there was no real goal or whatever to the single-player. You don't need much with a platformer, but you need something. Sounds like LBP2 has that now.