I like this figure overall and own two (and the coat may not be great, but it is WAY better than the hasbro version
) but I do think there's multiple issues with the headsculpt beyond a somewhat bland/dead expression and dull/uninspired paint app.
The human face part feels a bit too large for the overall head size (Carter's human face area seems proportionately smaller onscreen,) the front tentacle isn't quite long enough or fat enough, and the top part of the head seems like it needs to be larger/wider while his wattle/double-chin seems a bit oversized. I also think the facial likeness to Michael Carter (which IS visible in the movie) is okay but isn't great either.
I also think that the whole head is sculpted as too downward facing - it's almost as if the whole head needs to be reoriented/rotated upward maybe 20 deg and the eyes repainted to adjust to make it closer to how Bib's head is in the movie. It's tricky to judge because of Carter's height and the way he's often filmed from low angles.
I still plan to do a major reboot on one of mine, but it's one of those figs (like HT Chewy) that needs work on the head but is also "meh, it's kinda fine" when you actually take it out to plan the work.
It's still a really fun fig and the hands are excellently sculpted. It really was exactly the type of fig that made Sideshow shine in 1/6 SW, and a type of fig I wish they had done dozens more of (and done before prices reached the $130 point.) So sad they got lost in clones and left so many great SW aliens on the table.