Let's get to it:
The good:
Fin: Having one of the main protagonists be a Stormtrooper turning good who was also a janitor on Starkiller Base? It works. Way better than expected. He is written well and has great chemistry with Rey.
Rey: Love her. She's vulnerable but tough. Naive but smart. She's Solos successor and Lukes in one person. She cares and you instantly care about her. It will be interesting to see, if they really go through with her being Luke's daughter. There is much possibility there with Vaders grandchildren going at each others throat, but it may also fail very easily.
Kilo Ren: He's Hans son, Vaders grandchild and conflicted. It's alluded that he seeks this much power to do something grand, even if we don't know yet what and why. He is overestimating himself and at the same time frightened that he doesn't live up to his own expectations. He's a Vader fanboy in the best sense. His design alludes to Vader, but doesn't copy it. The helmet seems to be his burden and literally of much weight.
He was set up great and I hope he stays for a while.
In short: I really liked most characters. They were well written and set on an interesting path I want to see played out.
Harrison Ford: First time in over 10 years he showed some range and gave a damn. I loved seeing him getting back into the role and he nailed it.
The practical effects: Every time they could have used CGI and used a practical effect instead I wanted to applaud JJ and friends. In the first half of the movie it works really well and immerses you way more than an CGI could have managed.
BB 8: The best update R2D2 could have gotten. He's the same character, but done in a very good way. I'd love to see the making off of this guy. I'm sure some things were insanely hard to figure out in a practical way, but I'm glad this little guy kept rocking back and forth.
The first half of the movie: For me this was perfect Star Wars. Yes, there was this insane coincidence of Han finding the Falcon, but everything else was perfectly set up. The bad guys, especially Ren had a phenomenal introduction. Poe's short journey was fun. The main characters are set up really well and even the excuse for using the Millennium Falcon again made perfect sense.
The Lightsaber fight: It was a really good fight and maybe the best in the movies so far. The raw power approach and the wounded dangerous animal behaviour of Ren really came through. He was powerful and dangerous but not at the height of his abilities. Fin and Ren made the best of the situation they could and even if Rey had the situation a little bit too much under control in the end, I really enjoyed the way this fight played out.
The Bad:
Starkiller Base: Everything about this thing dragged the movie down. It doesn't make much sense from a practical point of view, it's literally the same idea already failed twice for the Empire, it still takes up too much time for introduction and is hokey at best nevertheless. It's destruction doesn't make much sense the way they explained it. And the destruction of the 5 planets was way worse than the destruction of Vulcan in ST:09 - we were just not invested in any of them. We've seen nothing of them. We don't care for them. A simple chase story from a Star Destroyer would have made much more sense.
R2D2/Card stuff: Minor point, but didn't make much sense the way they presented it. The way I understood it, R2 was using his energy for finding or reconstructing the card? And nobody understood what he was doing to the point that C3PO had to explain the plot point to another droid? Not very elegantly solved.
The Chrome Trooper/Plasma: Nicely set up, but badly used. She just took the shields down because some Ex-Trooper points a weapon at her? She cooperates way too easily for such a high rank.
Pandering to nostalgia: I expected high levels of nostalgia, but the way the story was set up, it was a bit too much. They played it a little bit too safe. It was at times just Episode IV retold with sprinkles of V throughout.
So aside form Starkiller Base it's only minor stuff I don't want to nitpick about too much - some things didn't make too much sense, but they fit the atmosphere.
The Ugly:
Snoke: Why CGI? Why use him at all at this point? Because you have to have a imperator like figure? It would have been really interesting with Ren as the highest up, being the tormented characters he is, but oh well.
In the end I liked it. It's not the best Star Wars, that title still belongs to V, but this could become my second favorite one. Depends on the rewatches. And I can't wait for more. That's always a good sign.