Costume Quest is an interesting RPG with a few minor flaws that keep it on just the wrong side of the greatness.
-Amazing Art Style, very cartoony and friendly.
-Halloween Theme is awesome.
-Manages to be appealing to kids but enjoyable for adults.
-A little too simple in certain areas.
-Lack of combat and customization variety
-Rediculous difficulty curve
So firstly as I said the style is amazing, a lot of greens, oranges and blacks mix well to give the game a nostalgic feeling of halloween's past. You use different kids halloween costumes to have different powers and they change form between the overworld and the battles, both of which look great, almost cell shaded and comic like in places.
The story is similarly charming and cartoon-like with a lot of effort put into appealing to the child in you and the nostalgia that part of you holds. I won't give out details but needles to say it is certainly interesting and although it doesn't take you to many 'new' places it will probably give you a fair few chuckles while playing it.
However gameplay wise is were problems start to happen. It has solid enough combat, basically lifted directly from super mario RPG, with an extra damage/extra defence mechanic which has you playing very brief mini-games with each hit. Although the combat is solid it is also a little same-y, you'll find yourself doing the same thing over and over again but as you constantly get new costumes and abilites it doesn't really get boring.
A big plus that helps remove some of the repetative nature of the game is a lack of grinding. Although you have to fight a certain number of fights in each area (sort of) you don't usually find yourself grinding to gain XP as you will rarley find yourself outstripped by enemies...until the ending.
Okay so I'm not going to give the ending away or anything but between the last normal enemies you fight, groups of 3 level 10 enemes, and the final boss there is a 10 level difference. Meaning that although you can blitz through most of the game up until this point (completeing all quests is seriously not even a chore if you keep your eyes peeled) you will have to go back to previous areas to grind up at least 5 levels before you are even remotely ready to take on the final fight. This isn't helped by the final boss' ability to clone itself into 3, although that is the least of the issues.
One final annoying point is that the ability to hold a button to go fast in the overworld is tied to a specific costume which means your main character has to wear it the entire game if you want to be able to move with any decent amount of speed, a very poor decision.
Overall not a bad game, a little short and a huuuuuge difficulty/grin wall right at the very end but it has a lot of charm and if you can get past the issues you will find a great little experience. Worth picking up for such a low price and sure to be someones nostalgic memory in the future.