The only issue with the new boarding proceedure is overhead bin availability. I haven't had that issue with SW before, but that's probably because they give you two free checked bags. JB gives you no free checked bags unless you have the right JB credit card, then you get one free bag. So, people try to pack as much as possible in their carry on bags, and then shove them into the overheads. If they don't fit wheels in (the proper way to stow them), they put them in sideways, which now takes up two spots. Or they put their overcoats up there, so anyone needing that spot for a bag now has to move a strangers coat and stick it back in, if at all possible.
Hopefully, with the new boarding proceedures, there will be fewer 'gate gnats'...those that haven't been called to board but hover around the jetway entrance so they can be the first to board in their group, if they aren't trying to board with an earlier group (which I've seen. Then they stand there and argue with the gate agent, holding everyone up). It's so nice to just line up, in the appropriate slot, and then board. No hovering around the gate, or trying to shove past those who think they should be boarding now, not you, even though your group was called. Sure, SW doesn't assign seats, but I really like the way they handle boarding. I can remain seated until the last minute, then get up, get in my slot, and board. Some hate it, I like it. But sadly, SW doesn't fly from my preferred airport, just JB flies there. But, its such a small airport that there aren't any huge crowds.