The DMM Bug Belay is the most straightforward belay you will find. There's no teeth for friction when belaying so you have to be extra careful.
I havent used it enough to agree/disagree with the comments on the previous review regarding the wire following up in to the belay but thanks for the warning.
Personally I do prefer the Black Diamond ATC belay, Im more comfortable with the teeth and friction.
The DMM Buy belay is still a great beginners belay.

Its about as useful as a fraying rope.
A bit of safety info here, the wire on these belays is rather flimsy and supple. I found that when lowering off on more than one occasion this wire would invert itself and follow the rope up into the belay device. Disasterous if happening at heights. Fortunatley my partner was about a foot off the ground when this happened otherwise we may have been in the sheet. Have replaced with a BD atc-xp...
But still great for beginners -_^

The Bug is DMM's most simplistic belay device. It is capable of belaying single or double ropes with adiameter of 10mm +. However belaying isits only real use, as it gives very little friction it isn't suitible for abseiling or alpine mountaineering and it gets hot very quikly. Overall it is a fantastic belay device for general use and is well recommended for beginners etc.