There is nothing like leather furniture or a nice leather sofa. Leather just plain feels nice on the skin and is also very breathable and comfortable. Leather comes in a variety of qualities and feels.
What to look for
You get what you pay for with leather, the cheaper stuff is a little hardened, not super soft like a pair of driving gloves. Also, mane leather sofa sets are built with a combination of leather on the surfaces you touch, kit the seat, back and arms, and a matching vinyl on the back and side where you don't touch. This is called a "leather match" type set. The nicer sets utilize an aniline dyed soft leather and are 100% leather, no vinyl. Expect to pay more for the higher quality, but it's worth it if you can afford it. By the way, most club chairs are made of leather.
Again you get what you pay for. Cheaper sets will have a soft wood frame like pine. The deck, or seat platform can be either a "no sag" or sinuous wire zigzag type, or the nicer more expensive "eight way hand tied" platform provides the ultimate in comfort and quality.
Honestly, it does not really matter. Look for quality construction and leather with a nice feel to it. You can buy the name brands, but remember packed in that price is their marketing and advertising expenses. Quality is more important than the name.
Italian? Made in USA? Made in China?
Like name brands, where it is made makes very little difference. Many leather sofa sets made in China are far superior that the one that are "Italian Leather" or even made in the USA, and vice -versa. Where it's made means NADA, nothing, it's all about the feel of the leather and quality of the construction.
Leather in other furniture pieces
Leather is being incorporated into many other pieces than just sofa's lately. Many leather beds have a leather padded back on the headboards, some tables even have leather tops. Leather give other furniture pieces a rustic or eclectic feel and look.