Speaking from the Seleucid perspective, Egyptian chariots (especially the early generals) are exceedingly annoying.

The melee chariots are ahistorically handy to have around. I speak primarily from experience using the Seleucid/Pontic scythed chariots, but the Egyptian melee chariots seemed comparable to me. I found them to be absolutely perfect rebel-quashers. In armies, they're also useful. Use them on the flanks as anti-cavalry protection (abusing the absurd cavalry-slaying magic the game has endowed chariots with), then as the battle progresses do more or less what you'd normally do with cavalry, only better because the chariots cause fear. You'll get more units routing quicker than you would with pure cavalry, but the chariots themselves won't rack up the kills very quickly - it's best to use them in conjunction with regular cavalry to make sure the routing units are wiped out in a timely manner.

Whatever you do, don't charge your chariots head-on into a phalanx wall on the far side of a bridge! That's how my Seleucids finally killed off the bulk of the Egyptian chariots in my game...