The SL55 in all of its varieties is a very reliable camera. The lens that you have bought is an 80mm Distagon with a larger than normal image circle. It is offered by Rollei to allow the full use of lens tilt w/o compromising quality as well as to allow a full set of flash sync speeds.

I have not been following Rollei prices but due to rarity I imagine that the lens is worth more than the fine 80mm Planar.