To me, the best thing about AO is the fast shipping. The turnaround on order time is kind of mind-blowing--they don't waste a lot of time on "processing" or "packing" your order like other places seem to do (vegan-friendly and non). I ordered a pair of boots on a Friday and got them on the following Monday.
Also, I really like the selection of shoes. They don't only have alternatives to leather, but a decent showing of cloth shoes. The bags are really cute, too. They've recently added some pretty nice pea coats, something that I haven't been able to find in a non-wool in my area.