Strengths: Less expensive than 7 series alloy rings, Shifts ok
Weaknesses: But do not expect a 6 series aluminum ring to last as long as a steel or 7 series alloy ring. Mine is still in use after 2000km's, but I had to file the "sharkteeth" off with a metal file because it started to chainsuck on a relatively clean chain. If you want something that will last more than a few months, consider another alloy.
I find it difficult to give an article a good value rating (even if it is cheaper) if it does not last. 3 Chillis for the overall, because of the good shifting when it was in it's mid life.