I'm obviously really looking forward to this one, but I also think this one has the biggest chance of being bad. I love the casting of Donald Glover; he was my first choice and IMO the only guy in Hollywood that can pull off the role. I like Ehrenreich, I'm hopeful he can pull it off. I'm most worried that physically he doesn't really look the part, and I'm hoping that won't take me out of it, but I'm certainly gonna give him a chance to win me over.
Clarke I'm sort of neutral on. Obviously she's beautiful and all that, which is great, and the Thrones connection kind of makes it cool, but I'm a bit worried about her acting ability. But I guess since we don't even know what type of character she's playing I'll hold off on any real pessimism for now.
Harrelson's the wild card IMO. Great actor and I actually feel like his personality totally fits in the Star Wars universe. But it's Woody freaking Harrelson and I'm a little worried that he's just too familiar. But if they write him a good part (Garris Shrike-ish seems like a good place to start) and he pulls it off it could be amazing.
While I am curious to find out more about the back story, find out about Chewie and the life debt, see how the Millennium Falcon came into the picture and changed hands, I really hope they don't go overboard on the easter eggs and references. None of that "Anakin built 3PO" type of BS. It needs to be a good story; it needs to be fun and exciting hopefully even a little dark, though I have my doubts about that last part.
Lastly, I think they should (and I think they will) push it back to a December release, as right now it's slated for a May 2018 release. It just doesn't really make sense to me to have it so soon after The Last Jedi. Plus I'm really liking these Christmas releases, starting to feel a bit like a tradition and I hope they stick with that. Assuming that's the case, we're probably looking at 12/20/17... only 684 more days! Assuming movie theaters are still allowed at that point.