It's interesting to see what the community thinks about here. So far, 2 or 3 people seem to be affected, changed their way of playing doom. But I guess it's more outside judging by the lot's of brutal doom vids on youtube.
I admit to a doom sin, playing newly released maps with Brutal Doom only. It would be ok to revisit old maps with BD, but now I feel I am not seeing the balance the original map author intended. At least, now I started designing a new map, I still was wise enough to test it in vanilla doom, keeping a ZdoomEdit folder with my old configuration for that purpose.
However, the balance is not screwed in my opinion. It did change, but slightly as the weapon power changed too. It was pimped up. In a way that makes it more intense (but not as hard as nightmare difficulty, I still find that too hard to play) but somehow still keeping the balance most of the times. There are few exceptions, like for example a trap with 4 revenants is not the same anymore, so maps that use lot's of revenants are too unplayable now. I remember in the past strafe running and making the rockets my satellite bitch, but I can't do this now. Yes, some level may be unfair now, regardless the powerful weaps and aiming to the head (revenant can die with only 3 simple shotgun to the head, wow) but easier ones play well.
Maps with simple monsters (zombies, imps, demons) can be really fun. Later ones, hmm.. some higher monsters are easier (lost soul, archvile), some are harder (cacodemons, revenants), with most you can't be near (too fast and deadly melee). I only was surprised with the Spiderdemon, the discussion we had about that it should be harder than the Cybie. I was outside in E3M8, I hear BLAM BLAM BLAM like they were firing cannons! My 200 armor was depleted and I was hurt badly. Yeah I know, it's a gimmick, but sooo awesome! Really kick ass spider boss!!!
Though, I am still an oldschool guy. I do appreciate and I do enjoy some good old maps from before 2000 more because of their simplicity. I usually don't enjoy Zdoom maps because they have slopes and mirrors and stuff (it's outdated Doom and still looks ugly anyway, regardless the patches. Like an old lady with perfume) except if they have some nice architecture and clean design to show me. But BD got me badly. Maybe I should head to that ZD forum and dissapear :)