I really like all of the maps. They are all so distinctive. I prefer this style of art in games over forced realism.
My only gripe with Overwatch art style is that I do feel like I am playing a kid's game at times. I bet it is even more noticeable to people older than I am. That is easy to overcome with how well designed it all is. Sometimes I do wish it was more geared for mature audiences, but there are plenty of other games to get that fix.
I also love the world tour. Reminds me of playing the first few Tony Hawks. That game had some great maps as well.