I have no idea if it'll be any good, but I'm incredibly excited for it. The promotional material has been praised for "returning to the original trilogy roots", which isn't actually hard to do when you're not tied down to doing a prequel and still have the actors and can rebuild the sets. It looks like the original trilogy because the actors, spaceships, and locations of the original trilogy are all in it. Look it's Han Solo! Look it's an X-Wing! Look they're inside the Millenium Falcon! That's not hard to do with promotional stuff, what the film will actually deliver is another matter entirely.
Whatever happens, it won't be as harmful as the prequels were. They were tied in tightly with the original trilogy, they're always going to be a part of Star Wars that can't really be ignored. But the new films can be discarded if they're bad, though it'd be almost impossible to have another crack at them with actors from the originals. They've wiped the slate clean of all the Expanded Universe stuff and anything onwards from this point isn't tied in so tightly to the existing Star Wars saga. If necessary they can sweep it under the rug and do a reboot of sorts. The original stuff would still be the jumping off point, but they'd be able to do almost anything off that.
Saying that, I'll be looking forwards to going to see it anyway, and I really want the new stuff to do well. This is probably the only shot they'll have at bringing back Mark Hamill, Harrison Ford, and Carrie Fisher to tie the new films into the older ones. I will be going into the cinema thinking "please don't be bad" all the same.
I'm oddly optimistic about how they'll turn out, though I'm not sure if they'll feel quite like a Star Wars film, that might be impossible though. Having the iconic actors back will certainly help make it feel like proper Star Wars. JJ Abrams has some experience bringing back a beloved Sci Fi property and making it into a successful movie or two. Even with Leonard Nimoy showing up in both new Star Trek films, it didn't feel quite the same but that's possibly because of the significant time difference between the iterations. Almost every piece of entertainment made is a product of its time in some way, you can look at stuff you used to watch and think "That's a really 90's show, I didn't realise that at the time." and see how different it is to entertainment nowadays. The tone, the character archetypes, the way the actors play those characters, the very feel of the film will be somewhat dictated by the time it's made.