A lot of things right:
+ Spells over grenades: more shit on screen, more chaos and fun.
+ Even more build diversity: Secondary class was a great idea, the new slots of spells and dedicated melee weapons so playing whatever is viable.
+ Significantly better dialogue pacing than Bl3: serious and goofy moments were done appropriately with good timings. The writing wasn't excruciatingly bad this time either.
+ Amazing environment designs: the best in the series imo.

The Negatives:
- Build diversity is good but the reasons to replay is very low
- End-game was tedious, time consuming and got boring quick
- DLC are an embarrassment
- Garbage UI (same as BL3)
- AWFUL IDEA TO PUT LUCK CHANCE TIED TO A COLLECTABLE FORCING YOU TO PLAY LIKE A COMPLETIONIST TO GETTING A DEDICATED DROP IN AN AREA (Mandatory to have decent chances for a drop which makes replaying even less enticing)

Overall: 7/10 - Good!