What they got right: These are definitely older versions of the characters, alternate timeline or not. Sonic is actually more mature (even noting he can't handle chili dogs like he used to), but he's still Sonic the Hedgehog. Dimitri seems to have mellowed over the years, even if Lien-Da hasn't. Apparently Sonic has time-traveled in the past (relatively speaking), but whether it's a story I missed (I know only of his travels to other dimensions) or they just haven't told yet I can't say. But like Sonic says, best not to think about it.
What they got wrong: Nothing, really. While it's not a stand-out story, it's gotten past the set-up stage of last issue. OK, maybe I'm wondering why Shadow is needed at this point. Isn't his story done?
Recommendation: I'm almost hoping to see 30 Years Later become a spin-off comic, or at least a story that Sonic Universe visits again in the future.