BMW Merino leather is a full grain unprotected leather...thus it is smooth/soft to the touch but will require more upkeep because it doesn't have a protective coating. Watch out for passengers that have metal buttons, pins, rhinestones, and snaps or other ornaments on their clothing...because these things can scar/scratch or even cut into the leather.
See the info below for a description of Merino, Nappa, and Dakota/Nevada leather. Some modern BMWs are also using a Vernasca leather...which appears to fall somewhere between Dakota and Nappa. It has a larger "grain" and is not as smooth Nappa...but it is not a coarse as Dakota. It also appears to have a protective coating, but I don't think it's a synthetic polymer coat layered on like Dakota leather.