let me try and place my feelings here.
on the one hand, the combat is same as it ever was, really. which is fine with me. a lot of the attacks are different enough from previous games, which is nice.
but i don't like the linearity of the game. it's also smaller than PoR. sure there are like twice as many areas, but a lot of them are really tiny. you got two levels that are just straight lines. and levels reuse map designs even before you get into the castle, which is also a little smaller than before.
the ratio of new enemies to old enemies is leaning towards 60/40, and no boss sprites were reused. hell, the only boss ideas that were in previous games were Death and Dracula.
i have to listen to the soundtrack again. at first, i didn't think it was all that great. but i've noticed a lot of great tracks in here, although there are a few that are kinda meh. for now, i'll say the music is on par with PoR, and better than DoS.
concerning difficulty, i thought the game was easy at first, then got harder as it progressed. it was when bosses started doing over 150 damage per hit did the change occur. Eligor is [tornado fang]ing insane, hardest boss i've fought in a long time. i'm not going to say the game is unbalanced, because it isn't. it's definitely the hardest game since CotM, and that game was only hard because it was disgustingly unbalanced. Death was really easy, though. Drac doesn't have a second form, which is sorta lame, but i can live without it.
Shanoa is a terrible character. sure she's nice to look at, but an emotionless shell doesn't make for a good CV protagonist. it's like playing with Old Axe Armor.
while my feelings for the main game are kinda in the air, i love Albus Mode. maybe because it's one of the only 2nd character modes i'm actually good at. his main moves are really good, though i've never used his flame kick or the crystal cage thingy. and the guy can literally warp to any place on the screen. it's really fun to go through the Training Hall backwards with him.
i need to give the game a little more time. but for now, i'll say that OoE is about on par with the previous two games. as of right now, DoS is my favorite on the DS, but PoR is very close behind.