Since the Mac beta of Warhammer Online was released, I have been playing whenever I could sneak in a little time with it, trying to see how I liked it.
So far, I have found it to be far better for the sporadic gaming I can sneak in lately, and has some fun things they have learned to do better from watching World of Warcraft.
One of the things I like best is the mechanics around the different classes. Unlike other games, Warhammer Online has different classes for each race and faction, with each race having 4 class or roles filled. Mostly, those are a Tank, a physical DPS, a Utility class and a Caster of some sort. Each operates differently, so each is a new experience, though each faction, Order or Destruction, has roughly the same capabilities. Here is a breakdown of roles, classes, and mechanics, paired by similar styles rather than by opposing factions.
Tanks
Empire - Knight of the Burning Sun. This class has aura like effects mostly enhancing teammates.
Chaos - Chosen. Behemoths of armor who have debuff auras.
High Elves - Swordmaster. Each main attack builds from a previous, building and using balance to weave through fights.
Greenskins - Black Orc. A mishmash of armor protects these giants while they string attacks which build off each other.
Dwarves - Ironbreaker. These warriors build grudge points from each blow they receive, and can designate a friend who they can also receive grudges when they are attacked. These Grudges fuel their special attacks. Lower DPS but extremely hard to kill.
Dark Elves - Black Guard. Attacks from these weapon masters are fueled by Hate, which builds when they attack or are attacked.
Physical DPS
Empire - Witch Hunter. These are lightly armored, fast, high DPS characters, whose attacks build from 0 to 5 points, which can then be used to fuel high power special attacks. Adding to their powers, they can go stealthy to ambush their prey.
Dark Elves - Witch Elf. Wearing almost no armor, these female-only brawlers also build combo points, and can go stealthy, but focus more on debuff attacks to devastate their opponents.
High Elves - White Lions. This is the Pet class of the Order side, with a Lion pet who will provide a moderate tank or second damage source. Aside their pets, the White Lions themselves are balanced between melee and ranged DPS, using their pet to draw attention and then flank their opponent.
Greenskins - Squig Herder. The Goblins have pets named Squigs, which come in a variety depending on desired tactics. While only controlling one at a time, they can call melee, tank, ranged or debuff pets, complemented by their own ranged attacks.
Dwarves - Slayer. These self-sacrificing berserkers make up for their stature through fervor. As they attack and take damage, they build up power and get stronger, though over a certain amount they lose control and become easier to damage.
Greenskins - Choppa. Matching their Dwarven bretherin, the Choppa is a hulking goliath of destruction. Another berserker class, they get stronger but easier to hit as they enrage.
High Elves - Shadow Warrior. These ranger-like characters excel at either melee or ranged fighting, taking stances which elevate certain skills depending on situation.
Chaos - Marauders. These flexible and ferocious mutants change forms to adapt to a variety of playstyles, all close combat focused but choosing between defense, sustained DPS, or critical DPS
Dwarves - Engineers. These don't have another physical counterpart, their closest analogue being the Magus caster, but they are sentry, trap, and explosive fighters, a sort of utility DPS which provides long-range support and critical location defense.
Casters
Empire - Bright Wizard. These fire-focused magic users kick out extremely high damage, but if they aren't careful the fire-magic they use can combust within them causing self-damage. While the risk of explosion is dangerous, as they risk more they get higher critical damage and chances.
Dark Elves - Sorceress. Flexible elemental and dark magic casters. As they use Dark magic, it builds up within them, the chaos potentially backfiring and causing massive injuries.
Dwarves - Rune Priest. A utility healer, these casters focus on mending and buffing their teammates, but also have some moderate offensive spells.
Chaos - Zealot. Another Utility healer, but balanced well with offensive capabilities. To offset those damage spells though, they are extremely squishy if the enemy gets too close.
Empire - Warrior Priest. A balance of DPS and healing, these clerics must fight close to combat to build the righteous fury which fuels their healing, and must balance the roles to play effectively.
Dark Elves - Desciple of Khaine. Another fighter/healer, they must fight to fuel their healing abilities, but offer some debuff type attacks to help in combat as well.
High Elves - Archmage. A balance of offense and defense makes these casters awfully fun to play and powerful. Damaging attacks buff later heals, and healing improves attack spells, so a good player can help in both roles well.
Greenskin - Shaman. These Goblins balance attack and healing spells, each type of spell benefitting the other when cast in succession.
Chaos - Magus. An offensive caster who can summon stationery demons to defend or assist in attacking. Needs some range to defend themselves, and summons take time, so need to pick your strategy from afar.
Conclusion
24 classes overall, with 12 distinct mechanics between them. Depending on your play preferences, one of them should fit nicely and let you play as you like.
For more information on each class, Ten Ton Hammer has a great summary and strategy page: Warhammer Online Class Guides