This is one of the first, if not the first, MMOs to truly sit down and make sure that players work together from the start, shedding the ironic selfishness of a genre that's meant to get people playing together in the first place.
It's weird to say it, but until you play Warhammer Online and take part in the war itself - taking battlefield objectives, winning scenarios, and fighting in glorious public quests - you'll look back on how much time you spent soloing in WOW and sob. The backstory is that the Age of Reckoning has finally been reached, and the armies of Destruction have decided to lay waste to everything. The forces of Order are trying to hold back the advance.
Mythic have absolutely taken the Warhammer mythos by the horns, embracing every part of the grim fantasy without pulling any punches. While the mollycoddling is there in the sense of players being eased into the game through a selection of easy quests and hand-holding throughout the first few levels, you will be at war with other players well before level 10, and depending on what side you're on, you're going to do something uniquely Warhammer.
Orcs kick dwarves off of the side of buildings, the Empire has the warhost on its doorstep and watch as its crops burn and people are slaughtered, and the Dark Elves release gigantic dinosaurs to eat people laying flowers at graves. The atmosphere is one of having no safe haven, one that draws you right into the conflict and gives you the drive necessary to slaughter your way through lines of your enemies.
And the real beauty of war is that this isn't all fluff - you're at war, from the off, constantly, and it's fun. PvP (or realm vs realm as it's known in WAR, and the rest of this review) is an integrated, fun-packed and addictive part of the game.
WAR is still an MMO though, and there are core concepts it hasn't shaken off. You control one of 20 careers (classes), split reasonably evenly between the two realms (sides) of Order and Destruction. Choosing a side locks whichever server you join to that side, to stop people from playing cross-realm spy games with each other.
The realm of Order is made up of the Empire, high elf and dwarf armies, and the realm of Destruction holds the Chaos Warhost, dark elf House and the Greenskin Waaagh!. The latter is the only non-racial army - it's made up of orcs and goblins - and will probably end up being flooded by roleplaying types who insist on typing everything like the bovver boy orcs they're playing as. Careers are army specific (see 'Career progression'), split between the archetypes of tanking, healing, ranged damage and up-close melee damage. There's some that overlap, such as the Bright Wizard and the Sorcerer, to keep the lore-monkeys happy without blocking players from their favourite role.
The careers fit reasonably comfortably into the usual class roles, with a few notable differences. Careers are less dependent on the usual pool of mana or energy, and each has a special mechanic they depend on to do the most damage. While abilities use action points, they generally depend on some other source to do the most damage.
For example, the Black Orc, as he uses different attacks, moves towards 'Da Best Plan,' a state that lets him unleash his most damaging attacks. The Bright Wizard builds combustion with each attack, doing more powerful and frequent critical hits, but also damaging himself in the process. There's a degree of micromanagement that requires you to be a little more alert than the average thumping of keys. It's not rocket science, neither is it really doing much to advance the basic mechanics of MMO combat, but it's satisfying, playable, and most importantly it works.