In 1.5.2 and earlier version of IC2 you could make almost everything from uu matter. Right now in 1.6.4 making uu costs enormous amount of EU and cost of uu increased - for using it for stuff.
Bees can make a lot of stuff - basic ores + copper, tin, all stones - lapis, redstone, glowstone, uranium - right now radioactive bee don't make uranium cause change of IC2, oil & fuel from refined bee, diamond, emerald - from binnie & magic bees, all dyes, zombie flesh, spider string, wheat, bones, gunpowder and tones of other stuff if you have GregTech.
But gaining bees costs huge amount of time for mutating all spiecies - more than 200 spiecies - nothing for free.
When you have first alveary you can make awesome mutation machine which speeds a lot process of getting all kind of bees.
I like to produce tones of stuff from bees to use it as a building material - lapis, cobalt blocks.
Also i like bees for that than i can't make tones of mystcraft ages and my world save don't have 1 Gb.
Someone said that bees are OP - in end game almost all is OP - boilers, tree farms, spawners. The same thing is in vanilla Minecraft - when you have villagers you can make iron farm, when you have witch farm you have tones of redstone & glowstone, skeletons - bone meal & arrows, simple cobblestone generation etc.
I love bees - especially when you have Normal/ Hard mode in Forestry - mutating bees is very tough and needs a lot of time. But i simply love mutating them.