This describes them pretty well.

From AOCWiki:

Rangers are the finest marksmen in Hyboria, capable of stalking an enemy and delivering devastating shots with pinpoint accuracy.
From the skilled woodsmen of the Bossonian Marches to the shortbow wielding horsemen of the Stygian desert, their skills with a bow set them apart from other warriors.

With an arsenal of specialist shots that can pin an enemy down, start bleeding wounds or pierce an enemy’s heart, they are difficult opponents. Knights fall to their fletched shafts and all the magic in hell cannot save a sorcerer with an arrow in their throat. They can fight in melee with swords and maces and wear medium armor, but their strengths lay with the bow.

Rangers have a track ability, allowing them to track players or prey in the surrounding area. They also have access to traps.

Rangers have something called a hide-attack. They can go into hiding, waiting for an enemy to show up. If they shoot somebody while hidden, their shot has a chance of putting the enemy in a mezzed state, basically knocking out the enemy so they're unable to move or fight back for an amount of time.

Rangers also have different stances, each providing an advantage for different uses. For instance, the sniper-stance will increase the range of the rangers attacks, while the volley-stance will increase the area of effect damage the ranger does, to great effect shattering-stance grants all of the Ranger’s attacks a chance to knock down their target as well as damaging nearby hostiles. Since crossbows can pierce through enemies, hitting a player or creature behind the enemy, there's a piercing-stance for rangers using crossbows.

[edit] Additional Information
The Ranger is a merge of the Ranger and the Waylayer classes, which was merged to provide a unique and wide array of arsenal, combinations and abilities. The ranger is also a class who has the ability to play in FPS mode while using ranged, though it is not the only way they can engage in ranged combat.

Feat List: http://aoc.wikia.com/wiki/Feat_Tree/Ranger

Very fun class though the FPS view is real buggy at the moment.