Late to the party on this one as well.
Overall, though I'm getting really tired or the "Metrovania"-concept (and the series as a whole), I did enjoy it a lot. Of the portable Symphony-clones, this is definitely one of the better and more rewarding ones. It's main attraction is that its actually a bit hard. Never had many problems with muddling through it, but like XLord007 said, they do make you work for it. The boss fights were particularly satisfying. The difficulty with many of the normal enemies, though, did feel a bit cheap, since they basically just doubled their hit and attack points from easier Metrovanias.
I never had much problem with the much-dreaded linearity of the game. Most of the Metrovanias were after all not that open to explore in the first place, so this doesn't feel that different, although it is more noticeable. I think this was eased by the fact that most stages are pretty short and in an outdoor environment, it felt more like you were traversing landscapes rather than just walking down the same old boring castle halls. And yes, I know that is only a perception: in practice the locales are the same rectangular-shaped corridor-type stages, but for me the outside environment did make a difference still. As for the music... as the case was with Portrait of Ruin, I did start liking the soundtrack more when I played the game, but I still find it pretty weaksauce when compared to most other Castlevania soundtracks, or considered as a stand-alone listening experience.
Also another thing... This isn't necessarily a knock, only an observation. One thing that I've been thinking about regarding the atmosphere in most Castlevanias from the 2000s - and which seems very striking with Order of Ecclesia - is how far this series has moved in feel from it's horror-inspired beginnings to a more generic fantasy-type setting. If it wasn't for the fact that the bad guy is Dracula and that you occasionally fight undead enemies, there's not much in OoE's style, story, atmosphere, etc. that connects to it's horror-roots or significantly varies from a generic fantasy-setting. I know the old games weren't especially "scary" in any sense either, but it seems that they at least had an ambition (up till around 1999's Castlevania 64, I'd say) to create a "haunted castle"-type of gothic atmosphere, which made the games feel different than the new ones do. I think this is part of why many people feel the series has lost a lot of it's identity. Just my impression...