How much of a time commitment is it? Do you choose what to write about? Have people on this board found it worth it/ rewarding?
Answers to all of these will depend on the school. Here's what it was for me:
1. 300 hours of editing for the first semester (in 7 weeks), maybe 80 hours of editing for the second semester, and another 50 hours on the note. I was told this was nearly twice as much as the average person spent the year before. By the luck of the draw, I had a monster article with many non-case sources (which required reading lots of books / journal articles). But again, the amount of work depends on the journal.
2. Yes. Complete control. But if you want to be published, you play by the rules (select a good topic and/or relevant case).
3. Yes. Even this year (3L) when I am a board member with a consistent 20-40 HPW of mind-numbing editing, I find it rewarding. I definitely think law review has made me a better writer. It also helped me get a clerkship (I'm sure), so I can't complain. If you have the opportunity to do law review, I highly recommend it. If you do law review, I highly recommend you work your butt of 2L year so you get a board position.