Depends on your expectations, but I think the 49ers have a chance to be really good. Their defense has been solid under Coach Singletary, and their offense has made some decent strides (especially Crabtree and Vernon Davis). Combined with the fact they are in the NFC West which is a pretty weak division (Seahaws, Rams, Cardinals (without Warner and Boldin), and a soft schedule (4 games against the AFC west, another terrible division), I can see them winning their division. I think they will at least go .500
The defense has been good the last few years and is certainly the strength of the team. In terms of overall success, it all depends on if Alex Smith makes any progress or is labeled an official bust after this year, given the size of his contract and expectations. The 49ers also play in a very weak division so making the playoffs is always within reach but I would guess a 9-7 record is about right this year.