From my experiances so far (Im up to around 200BC, Conquered Gaul, Germany, and half of Macedon, and I have also played extensive multiplayer games).

There are plenty of not more tactics in RTW due to the fact there are more USEFUL units. It simply isn't Swords/Ranged/Cav anymore.
You now have skirmishers, light infantry (which tires much slower), heavy infantry, cavalry, siege weapons are viable, and spears are back! Also you can employ aux units such as war dogs.

Cavalry is hardly overpowered. Fighting lightly or non armoured troops it can be devistating on the first charge, after that its dead. Heavily armoured troops against even the later cavalry will tear them up in melee and wont even flinch and their charge.