It deserves all the attention it has receives; it may be the seminal work of contemporary American crime fiction. It is the first great use of sparse, unemotional language to tell such a story, still as good an example of a lean prose style as can be found. I believe Chandler is the greatest influence on crime fiction, but Chandler would not have been Chandler were it not for Hammett, especially The Maltese Falcon.
It's funny you mention GLITZ. It's a really good book, and unique among Elmore Leonard's novels in that the bad guy is truly bad. In every other EL novel the bad guys are more the professional criminal type, in it for the money. Teddy Magyk in GLITZ is evil.
I'd also recommend SWAG, FREAKY DEAKY and OUT OF SIGHT. Actually, there isn't a bad one in the bunch.
To my mind he is the best crime novelist. His prose is clean and completely uncluttered with not a superfluous word.
He also, when he wanted to, as in Falcon, wrote in an explicitly cinematic way. The narrative voice is that of camera. It sees and hears, documents and reports back to the reader. Mostly with a 50mm lens, that is, neither wide nor telephoto.
You can see it in the translation to the film. If I recall, only one scene from the book did not end up on screen and only one thing, "the stuff that dreams are made of," was added.
He is usually compared with Chandler. Chandler had his gifts, but Hammett's world and his characters were much, much more real. His plotting was also much better.
Chandler's prose was flashier, full of vivid colorful metaphors.
Personally, I much prefer Hammett's clarity and simplicity. The only person who compares (aside from Hemingway, who was usually much more romantic) is Robert Pirsig (Zen & the Art of Motorcycle Maintainance, Lila: an Inquiry into Morals).
Hammett is my standard, default model. That is, unless I have a specific reason to do otherwise, his is the style I go for.
Hammett only wrote 5 novels.
Red Harvest, The Dain Curse, The Maltese Falcon, The Glass Key, and The Thin Man.
Each is worth reading. Indeed, they are among the few crime novels worth re-reading every ten or twenty years, for, as you change, they change.
The Thin Man most pronouncedly. When I first read it, it was a nifty mystery. When I next read it, in my twenties, I saw the characters as depicted in the films, witty and charming, living the high life, mingling with the low. When I last read it, in my fifties, I guess, it was devastating. It was about two people who no longer had a purpose in life and I understood how it came to be that Hammett never wrote again.
Red Harvest is about a mining town in Colorado (I think, though it may not be named). It is a devastating depiction of capitalism rampant and decadent, a more realistic version of Brecht's City of Mahagony. Read it with the understanding that, aside from the adventures of the Continental Op himself, what he is depicting is real.
The Dain Curse, written in the twenties, is remarkably contemporary, something right out of the 80s or 90s, with it's drug addiction and it's charlatan psychic and his cult.
The Glass Key has been made into films several times. Most recently, Miller's Crossing, by the Coen Brothers, who failed to credit Hammett, although even the hero's room is exactly as Hammett described it.
Anyone who is interested in 20th Century American literature, crime novels, the novel, prose styling, or being a better writer should read Hammett.
When I don't like something the Bob Dylan does, if I go back and listen again sometime later, I discover that he was right and I was wrong. I'd say the same about Hammett, if you don't get it, then it's likely about you, not him.
The first play I had produced was a rip-off of THE MALTESE FALCON, with a rare cheese recipe being substituted for the rare bird. I wrote it right after I read the novel.
Several years later, two things led me to try my hand at fiction. One was reading an awful short story (I don't remember what it was) and saying, "This got published? I know I could come up with something better." The other was reading Hammett's short story "The Scorched Face" (found in Pronzini & Adrian's HARD-BOILED anthology, also a very influential book for me) and saying "This is incredible! I'd love to try to write something like this."