Well I have installed it and tried it. The new interface looks really sleek and awesome. Also, custom games are a godsend. They are so much fun. Stuff like 10v10 games, Pudge wars, Skillshot, Dota soccer etc. But pings aren't good on them so far, mainly since most of the servers aren't that near Pakistan. Plus, since there is no penalty on custom games, people leave all the time and you hardly ever get a proper match. Still, when it happens, its loads of fun.
As for the graphics, I literally haven't noticed any improvements aside from the water, which looks a bit better. Maybe they haven't implemented the graphical overhaul yet.