There seems to be a misconception that when you say Fantasy Literature, we're talking about 10-16 year old fanboys/fangirls taking about Harry Potter and how it is 'the best thing evah' while on the other side we have the older, more 'mature' readers thinking that these books are mostly a small step above children bedtime stories.
Take note, I spelled the 'L' in Fantasy Literature in capital.
Other than it being a noun, it is also a much misinterpreted genre. I blame the movies. They tend to pick the most generic of the lot which they can sell to the people as something great. Like a McDonalds Fries. It's good and tasty but nothing beyond that (other than clogging your arteries)
Movie adaptations tend to glamorize the stories a bit. You'd probably have seen the Lord of The Rings trilogy and appreciated the huge battles, great characters, how cute Elija Wood as a hobbit is, and how overly long it is. If you have read the first print of it, not the novels that came out during the movies, you will notice that the man did not write it while eating dinner and watching Wheel of Fortune. It's pretty damn amazing the level of intellect and imagination that Tolkien must have had to almost single-handedly define the fantasy genre for all writers after him. When was the last time when you hear a person say elf you think of those small, pointy-hat wearing, candy eating characters? No, you think of a lithe, androgynous, pointy-eared creature with flowing hair. Unless you watched 'Elf' and you're thinking about Will Farrell which is anything but. He basically carved his face in the genre. His very own Mount Rushmore.
There are a lot of fantasy novels that uses different styles. There is the almost lyrical prose of Tad Williams that made you feel like you're reading a poem without all the boring feeling of...reading a poem, to the gritty no-hero-is-safe exposition of George R.R. Martin who I think is the biggest thing right now after the death of the great Robert Jordan who wrote his massively (overly) long LoTR-esque series 'The Wheel of Time'
Fantasy does not mean medieval swords and sorcery. There are a lot of writers who uses the modern day as the common setting. Just pick up a Dresden series book written by Jim Butcher or a Nightside series book by Simon R. Green and you'll know what I mean. They still have sword and magic but now accompanied with a gun. That's like a value meal with a sundae.
If you like reading, give fantasy a chance. It's like buying a new pair of shoes. Sometimes, they just don't fit or they may be exactly what you need to bring you to footwear nirvana. If you don't know where you start, check this site's recommendations. Execpt for a book or two in there, I've probably read everything.
http://www.bestfantasybooks.com/top25-fantasy-books.php