I've had the Sears/Craftsman C3 cordless tools (variable speed drill, right angle drill, light, two circular saws, hedge trimmer, reciprocating saw, jib saw, 1/2" impact wrench, etc.) since 2006. LOVE THEM. I'm still using my Ni-Cad batteries, but this year I noticed they are starting to get a little soft. A friend started out with the Li-Ion batts and is very happy with them. I'll move to them shortly. None of the Ni-Cads (some are from 2006, some from 2010) have completely died yet.
I'm not a 40 hour a week professional mechanic ... just a hobbyist with a race car. I can bust the 1" lug nuts off and back on all day long at the track. I torgue to 90ft/lbs and rarely tighten more than what the impact does.
I really like the C3 series and plan to buy the angle grinder next. One type of battery which is interchangable across all the various tools. The multi-chem charger is the way to go. The Ni-Cads see to fully charger in about an hour. The hedge trimmer really turned out great. The only disappointment in all the tools so far is the leaf blower.
I think the prices are very reasonable for the value allowing you to build quite the collection of cordless tools for a modest cost. One of the things that drove me to the C3 was a "single charger". I didn't want to have seven tools, four different sizes of batteries, and three different chargers to manage.