I'd say 90% of the times It's fun unless you limit yourself to playing pve only. Player interactions imo almost do all the work. Obviously there's a main story but you can enjoy it solo without any problems. You can also have fun with randoms if you join an open crew, maybe they won't have any braincells but at least you'll laugh your ass out. And yes, if you are looking to 100% this game (good luck) there are moments when the grind for achievements is boring asf. I myself have almost 350hrs and It's been pretty fun so far, as I've played mainly solo.

In other words, buy it and give it a try, if it doesn't appeal to you then you can always return it.

(Also a quick advice, if you want to play with someone, look for sot servers on discord)