Are in a word, awesome.

Last weekend I ran Red Dawn Rising (from Tome of Blood) and I must say, I have never had a more fluid, thrilling, fast-paced and fantastic experience running massed combat.

We had dramatic setbacks, traps, feints, tactics, players breaking out to save surrounded allies (and a fellow PC), epic duels, etc etc., and most importantly, due to the rules, each PC had several moments to shine.

If you haven't tried them yet I urge you to give them a go.