Let's get this out of the way: Castle Crashers is probably the most fun multiplayer experience on Live Arcade today, provided you're playing with friends. It's a fun brawler in the vein of old school beat 'em ups like Golden Axe and Double Dragon, but injected with a humorous tone and art style also found in Alien Hominid, The Behemoth's other XBLA game. Were it to work properly, I would have no problems recommending it to anyone even at the 1200 MS points price tag.
However, it doesn't work properly. If you're only playing in single player, you won't notice the most glaring issues with the game, but you'd also be missing the point of the game, which is the multiplayer. The net code, however, is so buggy, that using the quick match function just won't work most of the time, and if you're hosting your own game and inviting in friends, you're lucky if you can play for more than ten minutes without the game crashing you back to the main menu. Even in single player, there are glitches, which include the game not saving your progress, which can cause you to lose all the items and level ups you've gained in the time you played. How this passed Microsoft quality control is entirely past me. It is simply unacceptable that a game on XBLA, with an above-average price point no less, should suffer from such glaring issues that persist both online and off, especially a game which leans heavily on the strength of its multiplayer component.
Were these problems not present in the game, I would give it five stars. The multiplayer is a blast, really some of the most fun there is to be had online including retail games, again, with the caveat that you're playing with people you know or at least nice people. The game is lengthier than most brawlers, but doesn't get too repetitive thanks to the unique art style, changes in scenery, level up mechanics and a plethora of unlockable weapons. But the game contains show-stopping bugs that make it almost impossible to recommend at the asking price. It's a slap in the face of the consumer that these problems exist, and for the sake of all involved, I hope Microsoft and The Behemoth roll out a patch very soon, as it is just a terrible shame that such a fantastic game should be ruined such.