Charlottesville Area Masters of Real Ale

Are they merely premeasured amounts of a sugar to add to each bottle instead of mixing priming sugar into a bottling bucket?  Or do they produce carbonation, not relying on the residual yeast, by some other means?
Do they work any faster than the bottling bucket/priming sugar method?

I have never used them, but I think they are a premeasured sucrose solution (I could be getting the wrong sugar there).  The idea is that it allows you to add a measured amount to each bottle, rather than a larger amount of sugar to the entire batch, which could result in bottle bombs if your sugar is not evenly distributed amongst the bottles.  The carbonation drops also let you play with carbonation levels for different beers (stouts have less carbonation than belgian beers do, for example), though you can do the same thing with traditional priming sugar, but controling the amount added.

Anyone else have experience with this product?

I used them for a couple batches and vowed to never use them again.  They left white sediment in clumps (no, it wasn't yeast) at the bottom of the bottle and never fully disolved.  On top of that there was little to no carbonation in any of the bottles.  The ease of use is tempting but quality is much better and consistent with dextrose powder to the bottling bucket.

The Cooper's Carbonation drops are all I ever use.  I've never had a problem with them.  They are just like other means of natural carbonation and require a residual amount of yeast to react with them. 

The upside is that they are easy and consistent.  Also, for you keggers, you can bottle a few of your beers when you are racking into your keg so you can age and share.  (You could also wine thief out of the carboy and bottle one or two there.) 

The downside, like Tom mentioned, it is harder to control the amount of carbonation.  It will be consistent across beers, but some styles should be highly carbonated (cream ales) and some shouldn’t be (English session beers) these.

I've never seen the white sediment Peter is talking about.  I shake them up to make sure they distribute around the bottle, too, but I don’t think you need to.

They will carbonate your beer (given you keep them at a good room temperature) in two weeks just like putting a corn sugar mixture into the bottling bucket. (I find that using DME for bottling instead of dextrose takes longer to carbonate.)

Since I use these carb drops, I actually skip a stage and bottle directly out of the carboy.  No need to expose the beer to oxygen by putting it in a bottling bucket.