Leather is not just leather. Different grades and cuts give it a different feel and texture and also impact how it ages. Some buzzwords you may hear when shopping for leather furniture are "top grain", "full grain" and lately "bonded leather". These terms basically describe the type and condition of the hide.
Top grain simply means it is the outer most part of the hide, and that it is not a split or under part which has less strength and durability. When the processing is started the top of the leather is sheared from the hide leaving a split. A split is good for a back or side, not a place where you will sit as the hide will stretch and lose its shape.
A full grain hide is left with all its natural characteristics and markings in the processing stages. You will see a variety of grains from small to very heavy and this is ok. This shows that you are getting a genuine, minimally processed hide with natural markings. You will see many types of grain patterns and can determine which fits your preference.
The majority of the leather sold on the market has been buffed to eliminate heavy grain or imperfections and give a smooth uniform appearance and feel. Some hides are embossed with a simulated grain to give a very uniform look. Nevertheless, these are all good, long lasting alternatives to fabric and micro fibers. For those who suffer from allergies, the dust that collects in conventional fabrics can easily be kept in check with leather.
Remember that leather is a natural product so it is never perfect. Scars and various grains are all normal characteristics of genuine leather. The more expensive and natural, the more this rings true. Finally, beware of ultraviolet rays that can dry, crack and fade just about anything and leather is no exception. Look for a conditioner with UV protection. The good news is, leather can get better with use and age as it loosens up and develops a softer feel if taken care of properly.