It's convenient that he steps down now, mere days after the election that swore him into power once again. If he stepped down during the election Prince Ali would have won. This way, Blatter can call his own election and personally vouch for a new candidate to take over.
To me, Blatter was just the face of corruption. I simply cannot see someone from inside FIFA being able to resolve the corruption problems, mostly because these people are the problem. This isn't a new thing, and this isn't something that arrived with Blatter. Some journalists have been investigating corruption in FIFA for decades. Hell, most countries have been a part of it. It's only surfacing now because the bribery is so blatant, and our bribes simply weren't enough.
People will cheer and say that "we finally did it", but I cannot see anything truly changing. The only way FIFA will change is through the authorities.