The Good: Fantastic graphics and 3D effects, fun combat, lots of hidden secrets, interesting story
The Bad: Too much backtracking, story will mean nothing to new players of the series, combat can be too difficult at times, not much reason to play again, a bit short
Castlevania has struggled for years in the 3D department. Lords of Shadow was the first solid Castlevania that was in the 3D that did the series justice. Some hardcore fans shame the game, but I think it is one of the best action games of this generation. Mirror of Fate brings that same awesomeness to the 3DS with great combat and solid platforming.
You play as four protagonists through the whole game. Simon, Alucard, Gabriel, and Trevor. The game has simple 2D platforming with jumping and swinging, but the combat is solid enough. You have two attack buttons and a special power button. The special powers vary from axes (CV1 anyone?) to passive powers like being invincible for a short time or turning into a werewolf (Alucard). The combat is punchy and powerful and feels great. However, the game is incredibly hard. It requires a lot of skill and mastering the combat to get through the game because it can just get down right tough, but it's beatable. Apart from the combat you are mainly solving puzzles and finding secrets.
Puzzles involve pushing and pulling objects into right places, flipping switches in a sequential order, and some times even labyrinthine mazes. The map is very useful since you can place notes and it will tell you if there's a secret or something useful nearby. Upgrading health and magic seems like a standard affair but you have to find these chests and make an effort, they aren't handed to you. There was some annoying backtracking which felt a bit cheap, and the fast travel system is nearly useless since you never know which level you will end up in. I did get lost a few times and the puzzles can be real head scratchers, but platforming fans shouldn't struggle too much.
The story is pretty short and there's no reason to really come back. People who never played Lords of Shadow won't really get the story since the ending is extremely sad. The graphics are amazing and these are the best 3D effects I have seen on the 3DS thus far. They pop out and just make the whole game come to life. I honestly didn't see much that wasn't in 3D in some way.
Overall, Mirror of Fate is a solid yet difficult platformer that will make any Castlevania or platformer fan happy. The story is interesting, the 3D effects are amazing, and the combat is solid. Just be prepared for some backtracking and short game time.