First things first...what this game ISN'T...
This is not any form of D&D, or an old-school retro clone. This is not high magic fantasy. This is not level-based D20.
What it is, is a game of Arthurian fantasy filled with knights, damsels in distress, mysterious magic and an elegant system for backing up role play with mechanics. The Passions and Traits are a beautifully simple way of having consistent (well, consistent-ish) characterization while not feeling intrusive during play.
The game's mechanics are simple, but not simplistic. Combat is realistically brutal and harsh, but not arbitrary. When you win, you won with skill, and when you lose, you lose because your opponent was likely more skilled. I like too that the damage dealt with hand weapons is based more on the character than on the weapon type, with modification made for the type. It feels more right to me.
Character creation can be long, but as a process in itself is fun. It isn't just a case of slapping down stats and then figuring out where you fit in the world. You truly build a character from the ground up with a background, history and a place in the rich campaign world that is part and parcel of the Pendragon system.
And speaking of that campaign world, it is richly detailed within the book, and well supported by the author and the community with many additional books and adventures. But that said, it would be convertible to other realms. I'd prefer this system to run a Middle Earth campaign.
I will say that I went with 4th edition over 5th because this edition includes magic rules, which the 5th doesn't. Personal preference but I like to have the magic rules. But I really like the fact that the changes between editions are evolutionary not revolutionary so there's a lot of compatibility even back to the 1st edition!
This is the game I've been looking for since I got my 1st Ed AD&D books and wanted to play a chivalric knight.