The only thing I really agree with here is that Borderlands can be a bit repetitive. While its true the game can be fun online, you also have to deal with the people. The people who spend every waking hour of every day trying to find that one better gun that will make them the envy of the entire online community, or so they think. When one tries to play with these people, they constantly feel the need to step on our balls with golf shoes and tell us how bad we suck because we havn't played as obsessivly as them.
To counter these hardcores we get the utter noobs who bought the game and dived into the multi-player right away without getting a grip on the basics of the game. These are the people who spend most of their time looking around and exploring. And while theres nothing wrong with that it slows down the group, and you never know when this noob is going to explore an area filled with guys too high level for all of you and you wind up getting stomped. You then have to carry these noobs through every area teaching them everything they need to know to be a normal player while at the same time fending off the hordes and mutant venus fly-dogs that spawn out of dens almost as fast as your gun can shoot.
The single player I found incredably fun and I rarely ran into the same situation twice... though some were incredibly familiar and some of the boss fights required me to activly search for glitchs for me to hind behind while throwing bullets and dogs with more armor than a tank. When you play through the second time they increase the number of dogs that crawl out of dens and make the bosses so rediculosly over powered you feel like your playing a level one Mage against an eighty Rogue in Warcraft. You die a lot but to be honest it wasn't that bad. The second wind system is nice and is actually exploitable if your fighting a Badass and need to get close ebough to shoot without taking damage. Its a workable tactic. The only boss that gave me serious pause was a giant flying bird, but after spending an hour running around the map trying to find a safe haven I realized it couldn't hit you through overhead cover. i then spent 20 minutes shooting every bullet I had into it while ducking for cover in a building.
Overall I found the game highly enjoyable, though I have to admit I did find the interface annoying, but what am I gonna do? Stop playing?