Steve. 150 times per day is the norm, for me, since I have shitty little BSI of 1.4, and players like to take a bite out of me when they have the chance. Don't get worked over it. Try looking on the bright side, one of the achievements in the game requires losing in Duels and Colosseum battles, so it'll have to happen at some point! Cheer up mate.
For those of you having problems in the campaign, particularly missions 9, 14, and 15, the key is using the tank's Deflect ability. Not only does it make you invulnerable, it also lasts and nice 5 seconds or so and will usually kill anyone near you (or really, they will kill themselves). This proves extremely useful in some of the Challenges too. Another tip: For those with problems on the level with the invisible ninjas, get the minigun for the commando, and blindfire your way through the level. It works surprisingly well (and satisfying when you find those buggers trying to assassinate you.
I hear you BeBee. It's just utterly ridiculous. All the high-rated songs are covers. Why? If you can cover it, good for you. Why don't people try to appreciate creativity? There should be another section, entitled Covers. I'd get rid of all the covers if I could, it chokes the creative part.
 "Dawn of the Dragons"){kind=icon}
 "Step Seq."){kind=icon}
 "ir/rational Redux"){kind=icon}
 "Deadly Neighbors 2"){kind=icon}
 "Slush Invaders Game"){kind=icon}
 "Strike Force Heroes"){kind=icon}
 "Music Quest 2 Beta"){kind=icon}
 "Endless Migration 2 DEMO"){kind=icon}
 "Effing Worms 2"){kind=icon}