OK, after digesting this (I just saw it yesterday) I have put my finger on a few things that I didn't like. It was an entertaining movie, but I don't think I thought as highly of it as most I've heard discuss it.
1. I hate when the director/writer assumes that the viewer is too dumb to understand context so they have characters say things that are ridiculous so as to spell it out. An example: Snoke says something to Kylo Ren that includes the words "...your father, Han Solo...". Did he really think that Ren did not know that Solo was his father, so he had to specify that he meant Solo by "father"? Do you say to your friend, "...your dad, you know, Tom..."? I think it would have been obvious to the viewer that when Han tells Leia "he was here...our son was here..." and then he has the face off with Ren later on, that Solo is the father. Another example is that we had to hear, at least 3 times, what a great pilot Poe is, including the awkward, misplaced dialog of Fin during the battle (following the fairly preposterous display of piloting abilities by Poe).
2. As others have said, it was too fast. There were no stops, no slow moments that allowed us to understand the characters. It was almost like a shoot 'em up movie. Entertaining because of the action but I don't think the plot or the characters were developed very well.
3. Along the same lines as #2, I felt the characters were forced to evolve way too fast. It was like they wanted us to have the backstory of 15 characters all thrown out and as complete as you would have after a full trilogy. Are we really to believe that Rey went from no knowledge of the force to just figuring out that she could use the Jedi mind trick with no training or teaching? It was like watching the alien in the movie Species evolve over the span of an hour.
4. I thought Carrie Fisher, in general, was horrible, and Harrison Ford only marginally better. I suppose I can cut them a little bit of a break, as their characters were central to the plot, but they could have spent a little less time on them. I also didn't buy into Han reverting back to his smuggling ways after Ren turned to the dark side.