I think that I visit only 3 forums nowadays (here, let and VERY VERY rarely wht)(4 if you count reddit as a forum). I hate vpsb usability, hate wht mobile usability and (oh boy, I will burn in hell because of this) like let usability.
Before you kill me, let me explain my algorithm on how I use LET(vanilla is really a crappy PoS software btw).
I look for 3 informations: topic title, number of replies since I last saw a topic and last reply by.
I will read a topic if: a) I like the title or b) have a lot of replies or c) if I like to read what the last person to reply writes.
A and C are ok here , but B is horrible (and I will say that most of the time B is what fires my click).
Another horrible usability is that I have to click in a small circle to go to the last unread comment. OMFG, I can catch a fly with chopsticks but can't click that damn circle in mobile.
Maybe I don't know how to use IPBoard, but that summarizes my biggest concerns about ip board.