You didn't miss much.
The gunplay is great, probably the best in the series, but I found the weapons to be the least interesting of the 3 games (no, TPS is a piece of shit that I refuse to acknowledge). And there are kinda... too many of them, and for me diluting the pool so much made the looting less interesting and making builds a chore. I played BL1 and BL2 for thousands of hours, but couldn't play another second after completing BL3.
But its greatest sin, what's really unforgivable and destroyed the franchise for me, is that the writing is SO BAD it's infuriating. I loved to death the characters, the humour and the writing of BL1 and BL2. BL3 is SJWish, amateurish, dumb, tryhard, idiotic and worst of all, it ruins estabilished characters. It's unforgivable.
BL went from absolute, unconditioned love to absolute contempt.