There are no buses. Traffic in Conakry can be very heavy. The local transport vans in Conakry seem to be the most congested in all of West Africa. Taxis are very inexpensive, even if you want to rent one for a half or whole day. Expect to have to stop for gas almost immediately after you get in the car. The Government and business center of the city is unfortunately located at the tip of a long and narrow peninsula which is only connected to the rest of Conakry, which sprawls onto the mainland, by two roads. This can be particularly frustrating at rush hour. Line ups at gas stations in Conakry can be quite long and disorganized at certain times. Much of the infrastructure around the airport is being rebuilt, so trips to downtown or to la miniere might take unusual detours.
Bush Taxis "504", for the common Peugeot 504 model are used for transport from city to city. Keep in mind that there is a curfew at night, and if you try to drive into Conakry you will have to wait outside the city until morning. Local transport is usually able to leave Conakry after dark. Departure times are never set for local transport. In the early morning you might be told that a taxi will be leaving "toute suite" but will not get out of Conakry until well after dark. Intercity travel in Guinea requires a great deal of patience and a loose schedule. It is also possible to fly from city to city, but get to the airport early and bring cash for your tickets.
MotorTaxi/TaxiBike a much faster, and more comfortable way of travel is by motorcycle, which often serve as taxis.