I use Apple's Wireless Keyboard with my iPad via Bluetooth. It is fine for my needs and I can type an A4 lenght of text with it, but bear in mind...
If you are going to carry the iPad and the Keyboard around, out and about, not like moving from your coffee table to your bedroom, I meant taking those with you on a train, to an Internet cafe, and such, make sure you turn off the Bluetooth on the iPad.
Otherwise...
Because the F8 key on the Keyboard can Play and Pause your music on the iPad, so if the Bluetooth is still on, any knocks to the F8 key in the bag, or any presses somehow, such as your hands accidentally pressing the F8 key, will start playing music, even any knocks to the F12 key will up the volume to max.