I picked this up after growing tired of hooking up a keyboard to my 360 when I wanted to play final fantasy 11 and being forced to play just a few feet away from my TV.
The Messenger kid makes things alot easier when typing messages to other people or talking over msn, as it saves so much time compared to using the on-screen keyboard on the 360.
My only faults with this at the moment are the size of the buttons, which can make it a little harder to type if you have large thumbs/fingers due.
The other thing is the layouy of the symbol keys. While it sticks as close the the layout of a normal keyboard as possible, it had to put most of the symbols (Such as @, / and \) in differant places.
To deal with this they have put 2 buttons on the keyboard, one green and one orange, which act like the shift key, allowing you to get to all these symbols. Its not a problem, but it is something that will take time to get used to.
The best thing about this is the fact that you just plug it into your controller, saving on the amount of cables running about the place, making things more conveiniant.
Also, the keyboard has a messenger button, if you have already started chatting with someone, pressing this will open up a dark window at the bottom of you screen, rather then the 360 blade filling the screen. This is good because in the case of movies, you can continue watching it as you send your message missing anything.
Thrown in, is the head-set which is made specifically to use with the keyboard, as the standard wired head-sets wont plug into the chatpad, which is a nice bonus, as it can be used without the keyboard if you like.
In all, I think this is a great add-on for the 360, especially if your someone who spends alot of time typing away to friends, and is a bit of a must have for people playing Final Fantasy XI on their 360.