Bosses in BL1 are not at all like bosses in BL2. You won't face an enemy like the BNK-3R or Wilhelm anywhere in BL1. Most bosses will be like the Sheriff of Lynchwood, where there's maybe one gimmick where you figure it out in 3 minutes and go, "Oh, ok," before steamrolling that enemy and moving on.
The only "tough" bosses are Crawmerax, who has an even more exploitable glitch spot than Terra's rock, the Destroyer, whose only difficulty lies in actually having enough bullets to take it down, and maybe sometimes Knoxx, depending on how kind the Badass Destroyers plan on being to you. Otherwise, the bosses are barely powered-up bandits.