I bought two sets of these (one red, one blue) via the Amazon offer, and i think they're brilliant. As others have said, they don't really provide enough light to read by, especially as they're coloured, but work great for just having a little mood lighting as it were. I have the red ones in my bedroom and leave them on overnight when i sleep. The batteries last an age in them, not done any timed tests, but i can go for a couple of days before they run out, with leaving them on all night both nights and most of the evenings. Take into account it can take up to 12 hours to fully charge them though.
They're also great for using in the bathroom, as they charge by induction (like an electric toothbrush) they have no exposed electrical components, and i use all 6 to create a very relaxing mood.
The only gripe i can think of is how long it takes to fully charge the candles, apart from that a great product that's much safer and in the long run cheaper then conventional candles.
I've also uploaded some photos of the candles as the colours on the site are a bit brighter and pastel like than the candles really are.