Depends on how you use them.Chariots are an all or nothing proposition. Either you max them out and run them in a formation where you multi-charge and blow people up, or don't bring them at all. Chariots are not good support units, so don't use them as such.
Either chariots are your main plan, or they aren't in your plans.
I would definitely advise them as support units. Against standard infantry, impact hits are almost a sure way of getting a few extra kills for combat resolution. As a single chariot, the support role is not advised, but i suggest running them always in pairs.
I run two lion chariots and love them.
Have finished off 30 dark elf spearmen no problem. And thats the key. Target priority. Everyone watching the game was shocked i didn't charge the black guard unit that was crying out for the charge. But i knew that although i might take out the same amount of models, the risk of damage coming back was higher. The spearmen on the other hand were like paper. Strength 3 vs toughness 4 is always a nice bonus. Punched straight through the unit and took 1 wound. I let my swordmasters deal with the blackguard.
Chariots are definitely worth while, especially cheap ones. The cold one chariot !!!!!
WHAT A BARGAIN, even if it is stupid.