"Smells Like Teen Spirit" is the first episode this season that had more than one wobbly plot. While the main plot relating to Elena and Stefan was great, the other plots got shafted a bit and weren't really able to develop.
The Vicki plot went from Matt being able to communicate to Vicki to Vicki gone. In many ways, it felt much like the way Vicki died the first time, a death which, I believe, came about too fast. She became a vampire--analogous to moving into the physical world--and then dies quickly afterwards, giving us little time to process what happened or even let Vicki get to do anything.
The way the Tyler business was really off. In one moment, everyone's concerned about how Tyler is sired, Damon explaining how Tyler has extra devotion to Klaus; in the next, Tyler is left alone with Caroline and no one checks on him again. Unless Damon hitting him in the back of the head did the trick, I don't understand why they didn't keep a closer eye on him considering his allegiance to Klaus. Now, Tyler is ripping bodies apart and no one knows.
Those two plots were the big problems I had with the episode. The rest--awesome. Turned-off Stefan is funny to no end and he's way more likable than the old Stefan. The episode ends with Mason returning--not in ghost form hopefully. Since he's able to knock Damon to the ground, he's probably not a ghost.