When Pathfinder launched, our gaming group was still playing 3.x. There was a bit of trepidation about 4E, although one of the members was quite comfortable with the system, he wasn't running a game. So, none of us had considerable 4E experience at that point it time.
Additionally, all the 4E experience I did have was entirely negative. I had been in three 4E games at local gaming conventions, and every single one of them was a disaster. Even though the reasons these games were so horrible had little to do with the system (all three DMs were terribad), it was hard to look past the association.
Then here comes Pathfinder. I noticed it existed, but didn't really do anything about it. I was enjoying the games I played in, so I was happy. However, the next gaming convention I went to, the 4E games were almost entirely gone. In their places was a large, apparently happy community of Pathfinder players. Since I like to try new things at conventions, I signed up. It was some big adventure with multiple tables of players all working towards the same goal (later found out this was an early generation PFS special). Even playing a level 1 pregen, I had a pretty good time of it.
However, that doesn't cause a switch. I go home, sleep it off, and the next Sunday, I'm back to running my 3.5 Forgotten Realms campaign. Life goes on. However, a convention or two later, I'm thinking of making my own PFS character so I don't have to use pregens, and I actually started to look at the game. I was really happy with character creation, mostly in terms of being able to get the look and feel I wanted.* This is when I started increasing my involvement with the game.
* I generally feel if players are not happy with their characters, they are not happy with the game. It sounds a bit simplistic, but seems to hold true more often than not.