I thought they did a good job making the stakes feel high even though in the back of your mind you knew that they'd wind up with the plans and everyone would probably die. This counts for a lot for me, perhaps more than it ought to.
I came to like the characters , but not so much that I really cared a whole lot when they died.
I'm not too keen on people surviving when we think they're dead as I fee it makes the stakes feel low, so whojamacallit surviving that nice fall there bugged me, but it wasn't really a big deal.
Middle of the movie kinda dragged.
As skill pointed out, not a rehash of the original, which is good. I hope that 8 does its own thing too.
As for how the death star's able to kill planets so soon after that, I believe they said they were only using one reactor or just using "enough to destroy the city" of jeddah. Presumably it could have been used to blow entire planets to start with. I may be wrong, of course.