One of my favorite parts of Borderlands 1 & 2 were the wide open areas to explore and the laid back pacing of the main story. I could go to 10 different places and just walk around and i knew where the good, challenging areas were.
In Pre-Sequel (PS), i felt sort of dragged along against my will by the main story. They threw in side quests on areas that seemed out of place, or rather just for the sake of having them. The main story itself was sort of frantic, like we 'had' to go do 'this' thing as fast as possible or we will all die. So the laid back nature of the prior games sort of got lost, and i kept thinkng, "what is missing?"
One of the biggest things seemed to be the boss fights, there wasn't all that many of them. And i dispatched them with relative ease. The usual gimmicks of boss fights in Borderlands made you try to figure out how to dispatch them while trying not to die.
The story was such a integral element to the game, that the replay value, for me, is virtually none. BL2 i played probably 6 times. Part of it, i think, is the characters are weak. I played as the gunslinger Nisha, and through about half the game never even used her special move. Not only was it a little hard to use, it was overkill. And her constant commentary through the game was ridiculously annoying for some reason. I played exclusively with Zero in BL2, so maybe I'm just used to a quiet MC.
Overall i think i spent about 25-30 hours playing it, i did have alot of fun doing it, but I think this game was wholly unnecessary for the franchise, outside of a quick buck. I did really like the O2 mechanics with the jumping, that was really brilliant as it made moving through larger maps alot more enjoyable. I do think they need to add some more elements like lock picking, hacking, etc to spice up the interactivity of the environment. But that aside, it played almost identical to a former Borderlands game, but it just didn't feel like a full game.
Bottom line: Temper your expectations and play it for what it is, it's still fun but its not a fully realized title.