When I moved from 360 to PS3, the difference was noticeable. Game categories in Store had no screenshots. Updates for old games such as Uncharted 2 were painfully slow (assuming they've allocated their higher bandwidth servers for their newer games). Not to mention the PSN fiasco once they got hacked. I feel your pain.
What bothered me most is that you could not pause downloads on the xbox 360, you had to cancel them, so if i suddenly decided that I wanted to play the last game in my queue, I had to cancel all the others before it and then re-enter all the other games which was already in my queue. PSN was a lifesaver for download management in that regard.
PSN at the very early days didn't have screenshots for games that much is certain, but now every game has an overview which includes screenshots, videos, trailers, full esrb details, the developer, release date of title and full game feature details including peripheals, number of players supported etc...
As for me, perhaps what is the most helpful thing is download size, just last week ni no kuni was on sale, but i decided against it and opted for the disc instead because of the download size, that was easy enough without going through hoops, I can learn all i want about a game right there on the store to make an informed decision.
The differences here became more noticeable to me as I've been using my 360 more frequently these last two weeks since my PS3 got hit by a surge through a thunderstorm. Everything is not amazing on live, there's quite a bit that PSN and it's structure does better than live. It should also be noted that there are more games on PSN than on LIVE especially bigger games with larger download sizes, I've checked both lists from a-z, perhaps the sheer number and size of the games means there's more of a demand on the servers being accessed across the ps3, vita, psp and now PS4.