Most theatres here have both and I would always choose the reserved for a big showing, like an opening weekend premiere.
I think the advantage of having a guaranteed seat and not needing to line up, would outweigh the disadvantages mentioned earlier in the thread.
Also, an hour before the...
I love having reserved seating. It saves so much time that instead of waiting in line hours before watching, say, Age of Ultron, I bought my 3 tickets last week. All I have to do is just show up 15 minutes before the movie starts.
I've been reading some people say that they're not a fan, here...