Picked up my copy of OMSI 2 today, not a huge download by any means.
As things stand - there are quite a few bugs, and the promised backwards compatibility doesn't seem to be working at present. MR Software are promising to rectify this and some other issues as soon as possible. I've suffered a couple of freezes and crashes, and there are still issues with optimisation (if anything, the performance is on a par with OMSI 1) - but overall, things are heading in the right direction.
The new interface is great, and the expanded Spandau map has a lot of interest to keep you busy. The run out to Bahnhof Falkensee is quite lengthy, especially as I chose to do it in rush hour traffic using the MAN NG272 bendy-bus (a challenging vehicle to drive!). The new editor interface also looks quite promising, and I'm hoping to restart an aborted project of mine once the backwards compatibility issues are sorted out.