The turn length is just a third of what RTW was, but this easily balances out due to the fact that there are much fewer provinces to conquer, and the victory conditions are MUCH less than the original 50 provinces (and Rome). For the Celts, all you need is 18 provinces, and Alesia (forgot the BI name) and all of Britannia must be of those 18.
For WRE, you need 38(?), plus Rome, Carthage, Tarraco, and Constantinople, but this balances out too because you start out with a LOT of provinces under your control already (but you WILL cry after turn one when the rebellion and religious strife starts to sink in).
Some factions even go as low as needing only 10 provinces conquered.