Perfect co-op experience, accessible and most importantly fun! Castle Crashers pulls all the punches you'd expect +more
As far as looks go, you need to see it play to appretiate the animated flash-style graphics in High Definition. The animations are technically smooth, quirky (by nature) and even close up you can appretiate that this game despite the art style could not have been done 5 years ago. The High Def cartoon style may seem excessive on the 360 hardware, leaving you to believe more could be done easily. But the level of detail on closer inspection will quell those fears, infamous "jaggies" are nowhere to be seen and the 'arthouse gamer' can appretiate the Newgrounds-esh characetures.
Gameplay. For side-scrollers this has been typically been a mash of jump, hit and jump & hit. Castle Crashers is similar as it has these Golden Axe-type controls (A A B B A anyone?) but with a depth of several more buttons for different ranges of attacks adding depth and character to your, erm, character. Plus with the ability to block some attacks and use devestating magic attacks make the game all the more engaging and appealing to the hardcore gamer who loves a wide array of attacks for every concievable situation.
Depth, Castle Crashers has enough i assure you. A simple RPG levelling system where you gain XP through bashing dudes in the face and using you magic (which automatically regenerates at a rate depending on your level of magic). After you level up, you are given points to put towards either you defense, attack, magic or agility. Pretty self explanatory what each do, but don't think "attack is best i'll level this up first and get to 100% on this skill then worry about the rest" because your character will be horribly inbalanced and slower than other people you play with online who will nab treasure before your slow backside can make it across the screen. Also unlockable weapons with special attributes add more depth to a simple design, with unlockable characters as a mere collector's satisfaction as characters all have the same levels of each skill initially.
Online, if you don't have this you likely won't have an xbox or indeed reading this. Xbox live is where the game takes shape. You can pai up with a buddy on the couch and launch into a 4 player game with 2 (or more) on your sofa and 2 people on sofas anywhere in the world! Every bout you will be focussing on smashing things and grabbing every bit of loot before your "friendly team-mates" nab them. Its a smash and grab and fovours the ruthless at times but there is pleanty of need to work together as the game gets impossibly difficult when all 4 players are on screen. You can revive fallen buddies with an amuzing CPR animation; to make the game more intense, you can be knocked while performing this.
There are some issues with joining games, you have to be persistant until a patch arrives (soon). Host a match and wait 3 minutes and you'll have a full game.
For 1200 MS points I can honestly say this is the best value game on xbox live. The replay value is insane you will come back for more every day. Its a cut above any arcade game out so far and certainly most full retail games. Overall, a revelation in downloadable consoe games. The first of many I hope!