Too much of a good thing
Much like the Fat Princess herself eating too much cake, this game takes a good thing -- character customization and multiple gameplay choices -- and overdoses on it until you are left with a painful, disappointing result.
By now we all know that Fat Princess has a great watercolor art style and capture-the-flag style mission objectives layered with tons of different character customization options. The problem is that the game offers no direction for how these different classes and weapons should be used, no direction on which upgrades and unlocks should be targeted first as a power-up on the way to capturing the princess, and worst of all, no direction for how best to work as a team to win the match.
Let's take the example of a great and successful PSN title -- Warzone online play in Killzone 2. In Warzone you start as a grunt with no weapons and no abilities. You have to earn them by winning matches. This give you a great understanding of HOW TO PLAY THE GAME before confusing you with an overload of customization options. Fat Princess takes unfortunately the opposite approach -- if some freedom to customize is fun, then let's give the player ALL THE FREEDOM THEY WANT! The result is confusing, frantic, and frustrating.
There is also the issue of teamwork. Yes, if you work really hard at synching with your teammates, through a combination of skill and luck you can accomplish things together. But the fundamental issue is that the game should provide some framework to guide you there, instead of throwing you in the deep end and hoping that you can figure it out.
The first red flag you get is when you are doing the tutorial/ brief single player campaign. If you try to cooperate with your AI squadmates to break down the enemy's defenses one step at a time, it takes an incredibly long time to win the mission. If you just walk right in and pick up the princess, the enemy AI will stop attacking you and let you win almost immediately. That's the first sense you get that something is amiss in the Land of the Fat Princess.