Just finished playing it mate. Only played about an hour. Firstly, the game looks absolutely beautiful. As usual you have a nice dark setting and very bright neon signs and streetlights. There are some great vistas available from tall buildings and the inside of the buildings I have seen are well detailed.. The combat is as you would expect and the same as the previous games. The driving missions I played are extremely reminiscent of the James Bond driving missions but aside from slightly clunky controls, the batmobile has some nice touches and I can see with a bit of practice it would be easy to have fun with it/them. I'm guessing they may break the game up a little which you could be grateful for as it appears to be huge. 243 Riddler puzzles alone shows how big it potentially could be.
I don't want to give anything away really, but there are some lovely touches I have found so far, and overall, apart from some slightly annoying camera angles that 99% of open world games suffer from occasionally, I can't really find any faults with it.
Once again I have to say just how amazing it looks right from the get go. I reckon it's had a few "wow shit look at that" moments already, and that's after only one hour playing.