I usually like boss battles, especially difficult ones. It makes the game fun because it tests yours limits. What I DON'T like is having to watch a long cut scene over and over if you lose or having to go through an extremely time consuming level again. IMO that just takes away from the fun.

 Don't talk about that ever again! That was the worst time ever! D: 

So far I really hated only the first Heretic II's boss, the Celestial Watcher, because he was way too strong, in a cramped space with no cover, so the only, to call it so, "strategy" possible was a frantic button pushing, a thing i really hate. It was the first and only time I had to cheat to beat a boss. Obviously I don't like wimpy bosses too, for example Quake II's final boss was way too easy.
For example I liked a lot Walton Simons in Deus Ex, that is very tough and normally you must face more than once to kill, almost doubling the fun.

 Totally agree. What pisses me off if I have to play for 30 minutes then die, and just have to start it all again. I would prefer a checkpoint every 5 minutes. This is something where GTA and most RPGs fall down

Sounds like you dont like games that involve a strategy?

 I'll see your complaint and raise you 'restating a six-stage boss fight from the beginning after dying on the final form.'

*ahem*KH2*cough*

Excuse me  

@ thatmax, I just don't like having to treck through the same thing again and again

ye thats the case for most rpg's, train and level up, and yes i did that for FFX as well. as for LO you can only level up a certain amount in areas, so if anything most boss battles come down to strategy and a little buit of luck

It's part of the process.

Lose until you win.

I mean, I don't lose at games... But that's how I heard it's done