Idunno' if it's just me, but multiplayer makes it a lot easier. Yeah the enemies are stronger to compensate, but just having people there makes things easier since you don't have everything on the map targeting just you, etc.
Actually yeah. Me and a friend did Finks Slaughterdome and it was waay too easy. We also did the missions in Lynchwood, one that I had a lot of trouble in by myself, and it was really easy.
If you want the best gear I have found in BL2 you have to kill this guy a few times in a row.
http://borderlands.wikia.com/wiki/Terramorphous_the_Invincible
If you can kill him reliably, just save and quite right after you kill him so you wont have to keep paying to get back too him. Just keep looting and selling at the vendor machines outside of his lair.
I still never attempted that boss. Mainly because I only have one person on my friendslist that I play with, and I'm too lazy to ask him. I might when I'm able to sit again so I can actually play games.