I played LP2 with a friend and still we couldn't enjoy it.
Of course, I did not like the first one in the series either. The first was endless boring shooting against dull, damage soaking enemies with a few bosses that were alright but nothing special.
LP2 removes what could be cool about all this with their kitchen-sink style nonsense in the sequel. The mook combat is even more dreadful now, largely big, dumb switch hitting arena fights, and the bosses just lack any sort of excitement.
They try to throw a series of big co-op set pieces at you, like the railgun loading boss fight, but these turn out to feel more like gimmicky chores than anything else. The fundamentals are just all wrong. They break or water down everything LP1 did right and exacerbate everything LP1 did wrong.