I'm excited for the movie after seeing the trailer. I hated Reboot, but this seems like Smith actually trying to make a Kevin Smith comedy, not him making an obnoxious stoner comedy like Reboot was. He can still do great work, the Master of the Universe show he produces is great, so I think he has it in him to make an excellent Clerks III, he just generally hasn't felt like doing this type of movie since Clerks II came out.
He really seems to have a passion for making this film in particular, so while he could screw it up I'm hoping for him to pull out a movie that is more like the stuff he was doing in his prime. I could be proven wrong, but as of right now I'm hopeful. I don't think its going to dethrone Dogma as my favorite KS film, but I think it could match Clerks II or Jay & Silent Bob Strike Back (both of which are great, just not at Dogma's level in my opinion).