I wasn't a fan of chariots because of pathfinding issues (especially during sieges) and the fact that terrain didn't have enough of an impact on them (they should be useless in woods etc., but useful in open terrain). Also, the thing that they should excel at (disruption) didn't work so well, because disrupting formations wasn't as important in RTW as IRL - units would quickly reform during fighting and you couldn't really exploit the gaps.