On the way home tonight, I probably only saw a handful of folk with bright rear lights. Those were visible from some distance away. The rest had either poor batteries, pointing in bizarre directions, or just plane crap. Same goes for some front lights, completely drowned out by traffic.
You can get some nice and bright lights for not very much money, OK they might be a bit cheap, but they work. I have a few of the Planet X bikes Phaarts and they were £2.50. Got two on my MTB at the back ( the two led unit which is a copy of the RSP Astrum) and a few 3w front lights and a cat eye rear copy on my lads school bike.