This is a fantastic light for the Kindle (3, 4 and KK), fitting snugly to the top edge of the device without clips but through a slip on plastic flange with an internal rubber pad to grip firmly but without marking. It doesn't fit over a cover, but easily slips between cover and Kindle using my Tuff-luv Tri Axis, so I don't need to remove it. The 'clip'doesn't intrude into the reading screen, nor does the little arm which swings forward to switch on and illuminate. The light covers the whole screen superbly, but is focused enough not to throw light too far beyond, so a sleeping partner is unlikely to be disturbed. It is very compact and stylish, without long arms to worry about unbalancing the device too much, (though inevitably even the lightest lamp will change the balance a little) and being awkward to store. (I have arthritic thumbs so weight is an important issue for me, but this is not a problem with this light.) Its brushed aluminium surface makes it a really attractive object. It weighs a mere 50 grams with the battery provided, 10gms less with an Energiser lithium battery, so is likely to be less cumbersome than most other lights, both in use and when traveling. (Interestingly, the new Kindle 4 case seems to have a lighted option which replicates the style of the Octavo, but incorporated into the cover: that suggests Amazon recognises the quality and compactness of this design, though the Octovo produces less glare as the lighting arm is not at 90 degrees to the screen, unlike the Amazon cover light. This light fits Kindle 4 perfectly, anyway.)
Could it be bettered? IF it was rechargeable (it comes with a single AA battery) and came with its own pouch, I'd give it 6* - as it is, I'll have to settle for a mere perfect 5*: pricey, but worth every penny (remember it is postage free from Amazon!)
(A minority of reviewers have complained that the light can shine in their face if not viewed straight on rather than from below. This is obviously true, but the only way round that is to lengthen the lighting arm, increasing weight and cumbersomeness (if that's a word!) in use. There are plenty of lights around that will have that flexibility, so buy one of those if that's an issue. But it will be heavier, unbalance the device more, and be less easy to use when traveling. For my uses and circumstances this is pretty much perfect!)
Used with the new Kindle 4, the weight added to the device makes it weigh the same as the keyboard version, so pretty light, in every sense