No reservations at Jellyrolls. Do get there early because they have few tables which can fill up quickly. Also, to my knowledge, they don't serve food so definitely make this an after dinner thing.
The first time we visited the Boardwalk, we were all set after about 30 minutes. Now, instead of going back to our room during our mid-day break on our Epcot day, we'll go over to the Boardwalk and get lunch at ESPN Club (no ADRs taken here) and maybe stroll around for a bit. Definitely not worth going out of your way for, and not a way to spend a whole evening.