Depends on what the beatmap difficulty is.
As a general rule, Hidden is actually a good source of free points on most high approach rate maps because it reduces the visual clutter, and on high approach rates you don't have to memorise the positions of multiple objects for a long time - so depending on the situation, Hidden can make a map easier instead of harder. It depends though.
DoubleTime generally makes everything harder of course - unless the map was a painfully slow, OD 9. AR -1 map or something cruel like that. I can DoubleTime most normals and get ok grades on them, and a lot of the posters here can probably DT Hards.
Anyway, the general consensus I've seen so far is that you're "good" if you can pass Scarlet Rose. As Scarlet Rose is one of the hardest maps in the game (by my reckoning, at least) that means only a tiny fraction of the playerbase is or ever will be "good" at this game lol.
I've been playing for a bit over 4 months and a week ago I could pass maybe 40% of Hards with halfway decent scores, and get S on one or two of the really easy ones. However, I'm on a new laptop now and my skill level has dropped to where it was 2 weeks ago - not being able to pass any but 1 or 2 "Hard" (actually Normal+) maps - I suspect it's something to do with this laptop's mouse support... But that wouldn't explain why I can't sightread AR 9-10 anymore, and why all my beatmaps in general seem so much "faster" than before. Weird.
But anyway enough about me. I've long since learned that improvement in Osu takes a while, but there is a kind of satisfying feeling because you can SEE your improvement - every beatmap you play, where you get 1% or 2% or more accuracy each time you play, you're getting better.
So don't sweat the small stuff. Don't measure yourself against others unless there's real money involved! Osu is a multiplayer game, but it's also a personal journey! Be awesome in your own way!
Still though, there is a charm in striving for the position of #1...
http://www.youtube.com/watch?v=JuYeHPFR3f0~Talinoth
EDIT: WTF you're much better than I am. I should have looked at your profile before I made this post, lol.