Rurouni Kenshin/Samurai X is one that is pretty good. Has a lot of historical elements, although none are really done very accurately or with much attention given to realism. The swordplay starts to border on almost magical as well.
Afrosamurai has very well done fight scenes and essentially is all about the cut em up aspect of samurai. It revels in violence.
Samurai Champloo was mentioned, but it deserves another.
Honestly, there are tons of em. Just browse an anime list somewhere and see what matches up.
As for Samurai in general. Coffee and Sentinel nailed it. Bunch of thugs who originated as thugs and never forgot it. However, in the later parts of the samurai age, their behavior was purely guided by culture. They weren't really any worse than say the european knight. Albeit the knight was probably less likely to kill you for not bowing your head to him. He was more likely to just trample you to death for being in his way though. Few warrior groups, if any, are worthy of glorification. There were some good guys sprinkled in with a lot of trash in pretty much every one.