I'm using it for all my new projects. Memory management (almost) becomes one less thing to worry about.
From the point of view of someone who started off in a non-ARC world, not having to worry too much about memory management is a Positive Thing. I do wonder if it could make life slightly harder if all you ever known is ARC, though - it would be tempting to ignore reference counting as "something I no longer need to be bothered about", only to get bitten by it in those situations where it is still your problem to deal with.
tl;dr takeaway is that I'm glad it's here, but I'm also sort of glad that it wasn't when I was first starting out with iOS.