I too am keen on seeing if the Cook led Apple can deliver. Part of me thinks the company's standards have dropped a bit.
So am I, and I think they may have slipped a bit as well, but i don't think that was due to Tim being in charge.
Lion being the big stinker (but only one example) for me that people have been unhappy with - was in progress under Steve.
I think more likely what happened is that Steve had a vision for a unified, simple computing environment synced across all your devices since the late 90s (there are interviews out there regarding his vision for this from way back, can't remember off the top of my head where exactly right now though), and he was getting close enough to taste it. I certainly remember finding a video interview about 12 months ago with him from the 90s where he was talking about concepts which seem to resemble the foundations of icloud.
Knowing he had little time left, corners may have been cut (by the team) a little to try and push ahead and get there towards the end.
So, I don't think this is Tim's fault. Apple have plenty of talented people, and there is still some way to go with regards to Steve's vision of "it just works" across multiple devices before they run out of ideas.
Now that Steve is GONE, I think it's likely that there will be less rushing software out the door in an unfinished state to try and "get there" before Steve passes away...
edit:
seriously, a lot of the whines about lack of ugpradability, appliance-type nature, lack of filesystem access and iCloud sync, etc are all Steve's philosphy. bitching about that sort of thing and blaming Tim for it is not really fair, Steve was always against slots, cables, user servicing, etc.