I got level 3 with all styles, that's not a big achivement really...
I don't consider myselve very good, probably could be better if I had more patience, for instance I'm still beating the game in hard with dante and I waste to many health itens on bosses cause I go beserk instead of waiting, then I have to play some normal missions to get more orbs to get more itens for next boss, it's ridiculous, but otherwise it takes ages for me to get a clear opurtunity to damage the bosses.
and gunslinger sorta sucks on bosses, I tend to use sword master, or trickster (but I use trickster offensivly), I some times try dopple ganger, but the double some times start missing his hits.