This was the first time I used France in Civ4 and I really got to enjoy using Musketeers especially since I had no horses til I captured Nottingham from England whom I eventually vassalized.. :D

Here's the save if you're interested:
http://forums.civfanatics.com/uploads/137529/moggfanatic_AD-1290.CivBeyondSwordSave

They're one of my less favorite of the Musketman specials, but they are far from useless. They're great fast support for your combat stacks, cities that need defence, can deal with non-SOD's in the field in most cases, etc... They just suffer from the same difficulty that regular musketmen suffer from - they can't match knights in the open field, don't stand up to them as well as the cheaper pikemen, aren't as good at defending cities as longbowmen for their cost, and aren't as good as macemen attacking cities. Mustketmen are basically really good "fills any role pretty well" units which, paired with their ability to get to where you need them fast, make them something that usually compose 25%+ of my stacks when I'm playing the French. I'd take either Mehmed's or Zara's musketmen over them though. If only there were a protective French leader, and that was actually the mobility promotion and not just a built in extra move...

One thing that musketmen have going for them, though, is that when they become available, the enemy is not going to have any units that counter them. I mean, say your army consists of knights and macemen, and you're attacking a city defended by crossbows, longbows, and pikemen. The pikemen will kill the knights, and the crossbows will kill the macemen. On the other hand, if you're using a big ol' stack of musketeers/musketmen, they'll all have a decent chance of victory, even if it's not as much as a macemen attacking a longbow or a knight attacking a crossbow.

Yea, before i found out how useful they could be, I called them Muskequeers because I had thought they were worthless.

Another upside for the Musketeer/musketman is that it's draftable and usable on both defense and offense. After testing the drafting technuique in one game I've pretty much stuck to it, the late medeivel wars my army usually contains of large stacks of drafted musketmen combined with siege engines. Atlest on Epic or Marathon, In normal speed you tend to reach riflemen before you've had any real use of the Musketman.