The mimetic suit was used to cloak its user to its surroundings. However, they were timed cloakings due to the energy used in the suit's circuitry. When the energy was depleted the wearer was clearly visible.
A group of terrorist used several mimetic suits during their attempt to assassinate Supreme Chancellor Finis Valorum on Eriadu. Qui-Gon Jinn and several other jedi did battle with these terrorists.