Hosnian Prime's destruction being seen from Takodana.  Supposedly, Hosnian Prime is a Core World, while Takodana is in the Mid Rim.  That's...quite a significant distance.  Not to mention a faster than light weapon being visible as a beam of light.

 
1. It did feel too derivative of A New Hope. I was enjoying it most when it was putting in something new. The "trench run" was honestly the final straw for me on this. What really worries me about this, is I can see the next movie totally being derviative of Empire now. Rey is training with Luke (Yoda) when her friends (Finn/Poe/Leia) get in trouble and she feels it, leaving her training early to go rescue them, only to clash with Kylo Renn (Vader) and find out that they are somehow related or know each other. And while I don't think they would really make them brother and sister, I could see Rey being a young jedi trainee that was saved from Renn's massacre. 

2. There was no explanation of the polictical structure. I had no idea why there was a resistance the whole movie. Why weren't they just part of the Republic Forces? I had to go fucking online to find out that the Republic and First Order had a treaty, which makes sense given the relative smallness of the Rebellion compare to the Empire in the original trilogy, but for gods sakes you have to tell us that. This is also goes to the point of what the hell happened between OT and FA, which I know is supposed to be a bit of the mystery, but you can have character background mystery and still fill us in on the damn history of the universe. 

3. I actually enjoyed Kylo Renn. He seemed like a young, over his head, dark side apprentice who thinks he's hot shit but isn't really when compared to other force users. And yes, Rey is a bit of a savant (yet Luke also force pulled a lightsaber with no training) but Renn is really just not very well trained. 

4. I wasn't surprised in the least that Solo died. I feel like Harrison Ford has always been clear about being meh about returning to the franchise and was vocal about wanting to be killed off in Jedi. I'm sure he came back "just for one more" and for tons o money. 

5. Slightly less gripe, but there was also an obvious bit of cribbing from the extended universe that they imploded. I only ever read Rogue/Wraith Squadron and some of the Young Jedi Knights books but I have a vague understanding of what happened and I know things like Jacen going bad and the Starkiller are all in there. 

When they first showed R2 depowered and BB-8 went up to him, my brain immediately leapt to BB-8 IS R2 - like R2 was damaged and they took his core/memories/whatever and rebuilt him into BB-8.  Was so sad when that wasn't the case.  It would have made BB-8 so much more interesting and we wouldn't need both him and R2 then

I don't know what Luke's involvement will be in the grand scheme (I doubt he will be piloting a fighter) but R2 could always be there to get him (them) out of a jam, or just to be his quirky self. Whereas BB-8 is Poe's buddy and will most definitely see some more high-intensity fighter action.