I've been using it sionce they gave away licenses with 2GB CF cards - Can't compare it to LR as I've never been able to afford it. Very flexible and straightforward to use, the downsides are as already mentioned -
No catalogue as such - You have to be a bit strict on your own naming/filing conventions to find anything again
Quite a lot of "additional" folders (these only contain the "adjustments" applied to your RAW images (it's non destructive in that you can delete the "settings" folder and you've still got your original RAW's with no adjustments.
Not sure how much it is to buy (like I said my licence was a free one) but well worth considering if it's considerably less than Lightroom.