I have these out in the conservatory, where they make a really attractive compliment to candles (and are certainly safer!).
The solar lights last for about 2-5 hours, defending how sunny it has been during the day. I don't know how well they survive outdoors, but they should be moderately rainproof, and the solar cells seem well designed. To be sure, you could seal the edge of the solar cell with sealant or tape.
Check around for prices, which seem to vary quite a bit! I paid £14 from Longacres + pp (£18 total for 4 lights), which is a very good price, but I've seen other sellers charging much more. One did arrive damaged in transit, but the company were excellent to deal with, and more than compensated the loss, which they did very promptly and efficiently.
Overall, I'm really pleased with them.