Just finished the premiere, pretty damn good. The highlight for me was the Earth stuff, mostly because this is new material not covered in the novels, but also it was just really interesting. I especially like the work they've done with the Admiral, who was basically just an exposition piece last year, and have turned him into a somewhat interesting character. And with a transfer out to the Belt, it seems likely he'll be revisited in some manner as the season develops.
The Martian stuff was really good, and Bobbie Draper is every bit as great a character as he is in the novels. Though it's interesting, in the show we actually are seeing her more in a military setting and interacting among fellow Marines, which I only just realized while watching the show, wasn't something we saw very much of in the novels, despite the pivotal role she plays and the fact she was in a good deal of combat throughout the novels.
The space battle was awesome, I especially liked the bit with them depressurizing the Rocinante to minimize how much trouble would be caused when their hull gets breached. That was neat, and certainly an interesting idea.