Others say...

"Different Strokes"
Think carefully on this one--it seems like a neat idea to bathe your keyboard in blue light, particularly if yours isn't backlit. But...does it really do you any good? I'm a "cheating" typist--I'm lazy about home keys and often have to look down at my hands to double-check I'm not fadkjlajling all over the place. I love gaming in the dark--the better to be immersed in the full glow of the screen.
Looking at the Razer BattleLight, all I can see is a distraction. Because it's a bulb, and it's directly under your eyes, you have a glowing oval continuously in your peripheral vision (yes, even with the hood). The darker you want the room (which is why you wanted to light your keyboard, right?) the more you're going to find this little neon tube demanding your attention in the lower part of your vision.
I've got a backlit keyboard now, but I still stick with my preferred way to see the keys and still game in the dark: I have a desk lamp with an adjustable dimmer, turned down low and out of my field of vision. A little bit of ambient light goes a long way. :)

"Battle light review"
The battle light fails. It dosent illuminate all of the keyboard, and the parts that it does illuminate you cant really see anyways. The keys on my Tarantula have a bit of a glossy finish to them, and when you combine that with white letting on the keys, the bright blue LED lights just wash everything out. So you are about as well off just typing in the dark.

The only good thing about this light is its really unique. If you just have to have a swank LED light hanging off your keyboard, this is the light for you. Just dont expect too much funtionality.

"Not worth it..."
When I got the tarantula keyboard, one of the reasons was because the accessories that could be added to it. At the time I bought the keyboard I thought that the accessories had already been released but to my dismay they were not (bout 3 months ago) So when i found out the BattleLight accessory had been released I was quite excited. So on to the pros and cons...

Pros:
-"oooo a pretty blue light"
-Button to turn light on and off
-Adjustable head (up, down, turn left, turn right)

Cons:
-Only illuminates the middle of the keyboard! (From about to the "t" to "Delete", which is about the length of the light)
-Shows you even in the dark how much this keyboard collects dust..
-A bit distracting when gaming.

In my opinion, the BattleLight is just an eye catch and not worth the money. If you really want light, you would be better off getting a keyboard with illuminated keys but then again the Tarantula is quite an awesome keyboard. I just wish the keys were illuminated.