Will it be better than the original trilogy? Well, nothing's impossible, but realistically No. Nostalgia factor.
Will it be better than the prequel trilogy? Again, nothing's impossible, but here it's almost certainly Yes.
That would seem to make it an almost guaranteed win. But we're still talking about an established universe that everyone knows and no one will tolerate them fucking up. And established characters. With so many eyes on this and so many checks and balances in place, I don't think that will happen, either. Just give me a good movie, one that shows respect for the established universe and characters, and the next chapter of the story, and because it's Star Wars, I'll probably like it.
Also, and this might sound stupid, but I trust Harrison Ford's judgement. He didn't have to do this movie, and I'm sure he would not have if he read the script and he didn't like what they'd done with Han Solo. After all the joking around, he seemed sincere when he said this was a great movie and we won't be disappointed. That sounds good enough for me.