Castlevania Order of Ecclesia does an excellent job of blending action and RPG elements into a platforming environment.
But, rather than carry on about how much I loved the game or simply re-hash what has already been said and known about it, I like to just point out different aspects that may strike a chord with players, be them good or bad.
The glyph system:
This new "weaponless," system has its pros and cons. To call it "weaponless," is something of a misnomer in my opinion, because the magical glyphs are used for exactly that purpose. They may not all be traditional weapons a la whips, swords, axes and chains, but they are weapons nonetheless. In fact, some are indeed those weapons- just MAGIC versions of them.
It can be somewhat difficult to ascertain which glyphs should be used in what situation. The only way (outside of a strategy guide/walkthrough) to do this is by trial and error- a tedious process. Also, the game is absolutely FULL of different glyphs...but ultimately a player will most likely find a few that they like best and stick with them- leaving many useless glyphs.
Gameplay:
Calling this game a 2-D platformer doesn't really do it justice. After all, it's heavily action-RPG in style, and you don't merely follow a left to right pattern until the game is over. You can backtrack, visit multiple areas infinite times, you have a leveling system with experience, you have equipment with different abilities and personal attributes. This shouts action-RPG. It just so happens to be confined to the DS.
The mechanics are smooth and responsive for the most part. Sometimes thumb cramping can be common being a DS game that requires precision timing and jumping in some parts, but that's to be expected. This isn't a casual game, by any means.
Other Points
I personally found the game to be difficult in some places, but gradually easier as I got the gist of what was going on with the glyph system and became more familiar with enemies. I would not recommend it for the typical 8 year old. Don't be lured into the idea that because it's a DS game, it's easy enough for little children. It isn't.
Finally, being RPG oriented, make sure you are a fan (or at least can stand) the idea of "grinding,"- passing through areas multiple times in order to find rare items that drop randomly. This can be off-putting.
Summation
C: O of E is a fine game in its own right, but make sure that you are a fan of RPG-style play, have time to be immersed (no save anywhere feature), and don't mind a game that relies on a trial and error process to get through.