As others have said, I think the main problems are that it's just been too rushed, and also the fact that the dialogue for some of the characters seems to have taken several steps backwards compared to earlier series.
Previously, events like the battles of King's Landing and Winterfell would have been the stand-out set-piece of a full series, now they only have an episode between them. Episode 4 had to deal with the aftermath of one battle while building up the next one, and didn't have enough time to do either properly.
I don't have a problem with how most of the character's have ended up, but the condensed plot means the last few steps of their journey has been too rushed. Jamie running back to Cersei, Arya giving up on killing Cersei, Varys betraying Dany, Dany going beserk - all of these things would have been better if they'd had a bit more time.
I know every would-be writer (or blogger) on the internet has had their say on how they think things should have been done, so I'll only mention one tweak I thought of - have Daenarys execute Varys' little bird alongside him. It shows an extra step on her taking a darker path, and could also be a call-back (either directly or indirectly) to Jon executing Olly.