The can is all black with the M logo on the front in blue instead of green.
This was my favorite for some time, less syrup than the regular Monster, and a lot less calories (important, since I'm watching my girlish figure). I think the Lo-Carb Monster or "blue" monster, tastes a lot like a variation of ginger ale, a light pleasant taste, but not always consistent from the factory (a can from one store may be very flavorful, a can from a store down the road may be fairly bland). This drink delivers a lot of energy for a nearly carb-free beverage. It also provides a host of vitamins, like getting a suppliment out of your soda. Hansen, the makers of Monster, know a lot about energy suppliments and vitamens, as they've been making these products for heatlth stores for years. The value is good, and you can often get these one sale, for as low as $1.25.each, if you buy in the four pack.
Added June 26th, 2006
There is some speculation that this is the same beverage as Joker Mad Energy Lo Carb. It certainly tastes very close, and the ingredients are nearly the same. If you find Joker on sale, you may save some money over buying the authentic Monster Lo Carb. You also get a can with a cool cracked-out Jester, which Monster has yet to offer.
The Lo-Carb Monster is a great alternative to the Original Monster. With a fraction of the sugar and even less calories, it's a great way to get a kick and still watch your figure.