imo there are 3 ways to play this
solo - can recommend,
coop - from the beginning where it’s a first playthrough for both(so 1 ain’t blazing through) with a friend/like minded person, -someone you wont squabble over upgrades with - can also sorta recommend
coop - wait until the end for “endgame” boss - 
“depends”
anything else in between can be annoying, especially with randoms but even with friends, as besides from a first naked playthrough, once done seems all coop sessions just turn to a rush fest, like @Pylinaer mentioned, for clearing main story moving on in difficulty and/or blazin to bosses
and this is also the only place where you will encounter any grind. The game is fairly generous with plenty and decent or good loot while just goign through “normally” -“like a filthy casul”. Only during “endgame” stuff when you want to tweak x build/get xx specific items can it get a bit grindy trying to get some stuff.
but imo that’s not really where borderlands were fun. the endgame is a bit meh, and even with friends the coop play can be a bit uninteresting just going for x bosses, spray it up for few mins and done… playing story mode tho, starting a new character from scratch to try their skills now that was fun. -and if you can (find) someone to mess around with and enjoy the campaign playthrough then it can be really fun
it’s a decently fun looter shooter with silly stuff going on, “dumb comedy”, and an okay story and va, some parts of the first one are better than the sequel, and vice versa.
The first one ain’t exactly pretty, and has some qol features missing from the pc port you might want to change in config, but doesn’t bother all. But imo the first also has the better guns/combo -i sorely miss exploding rounds/snipers in the second. 
overall i had meni meni meni hours of fun with the first 2 games, so it’s hard for me to not be able to recommend them either way.
But if you are looking for oldschool quake/doom etc “purity” shooting this aint it. If you’re looking for intricate boss fights mechanics, this aint it. If you’re looking for “mature” setting or “grown up’s” story and something deep, or just something that is truly innovative and flips a switch for gaming medium, this aint it.
^but it could still be fun despite that 
-and hell, think i’d recommend BL2 just for Tiny Tina alone 
guess not 
)
…
-saves 40bucks for something else instead 
-at least i aint seeing separate entries for bl2 or pre sequel, only bl1
ahaha damn talk about salt… i will never understand that heroin additc "must have day 1"gamer mentality -just f’n wait, or skip entirely 
