Spok lights are not designed to help you see the road, they are designed to let other road users see you. That's not necessarily a bad thing, but it's something you should be aware of. I don't use Spok lights as my only lights, but I've bought a few sets of them and I find them very useful.
They are the lights you put on the bike you don't want to burden with lights.
They are the inexpensive spare lights you have in case your main light goes out.
They are the lights you give to your friend when you realize he's riding after dark and his bike has no lights.
They are the stocking stuffer gift you give your cycling pal because even though she has a bunch of lights already, these are handy and cute.
They are the lights you buy because you like the fact that Planet Bike sends 25% of their profits to bike advocacy groups and creates ads that talk about their products instead of spending bucks on some hip and sexy advertising campaign that doesn't seem to have much to do with bikes at all.
They are the lights you put on your lightest helmet and it still remains your lightest helmet.
In short, I like these little lights. Now if I only knew for certain how to pronounce the name of them. I think the name is pronounced like the thin metal rods connecting my bike's hubs to the rims, but I suppose the name could be pronounced like that of a certain logical Vulcan.
BTW the batteries seem to last a pretty long time and the Spok lights use the same CR2032 battery that is used in my Cateye Cycle Computer. CR2032 cells can be found in lots of places these days but they are small enough that buying a batch online is worthwhile.
Keep 'em rolling,