An outstanding, one-of-a-kind lens. It is almost always in my bag, and if I can only take one lens, this is generally it.
114° angle of view at ?2.8 is simply incredible! When you take a picture on Wednesday, you have to be careful not to get Monday and Friday in the picture! Seriously, mind those feet and fingers; they end up in a lot of shots! Shooting movies with this, using Olympus IBIS, is a real experience.
I could wish for the ability to use filters; I could wish that the flare situation was better; I could wish it was smaller; lighter; and cheaper; but really; any lens in this category is going to be similar in these respects