I recently started using explorers and I wanted to share my pleasant experiences. Most of the treads I have read on the explorer are along the lines of "they suck, they come much to late to explore anything". It is true, by the time you get explorers, there usually isn't much map left to explore. The key to using them is not to think of them as an explorer, but to think of them as a special operations unit.
THE FACTS:
Explorers get 2 moves, and treat all squares like they have roads. Unlike the scout who's moves are treated like there are no roads, the explorer can run across your neighbors territory in a couple turns.
They aren't considered a thret by the civs you are at peace with, so they can move freely through their territory. Rarely, if ever will they get forced to leave.
