So I've had a few days to ruminate on the new rules and come to a few conclusions. Mechanically the game is very poor, but GW is heading in exactly the right direction in terms of the game's spirit. First the good stuff:
1) No points. Others have mentioned this, but it is worth reiterating. Dropping the point system is the single best move GW has taken. It is an elegant way to encourage players to think about the game as a scenario or story first and a competition second. This is a technique used by a lot of old historical wargames and it works extremely well, despite the fact that it is so rarely used in new games these days.
2) Easy rules, faster play. The game is dead simple and although there are special rule exceptions, they are all extremely similar (usually rerolling dice). This is great for casual gamers who want something that plays fast and doesn't require a lot of rules-referencing in the middle of the game.
3) Free. Hopefully this part lasts. Unfortunately, GW has done a "Ravening Hordes"-like freebie version to use old miniatures in new editions for decades now, which is later replaced by (increasingly expensive) rulebooks and army books. While this is more a new game than a new edition, the same principle applies—a quick, free document to use your old models while you wait for new books. If GW sticks with the free-to-play idea, it will be excellent (although considering the fact that they sell $80 iPad apps, including $5-6 painting guides good for only a single model, this is doubtful).
I think these things are definitely in the right "spirit" and ought to be commended. Now, for casual gamers, all this would be enough. This is great for young kids and there are even a lot of adults that enjoy and prefer simpler games. Heck, people shelled out
almost $9 million dollars this year for a game of go fish. This type of gamer just wants to roll dice while having a beer with friends and really doesn't care about all the things that game nerds (ahem, game "connoisseurs"!) would rave about.
For the game collector and rules aficionado, the new game is, mechanically speaking, pretty rubbish. It is most definitely the checkers (sorry, "draughts") to Warhammer Fantasy's chess. Firstly, it cuts out the gritty thematic parts. Compare this game, for instance, to the next closest Games Workshop title: Mordheim. In Mordheim, you have rules for slugging enemies over the head with a hammer and giving them a concussion, rules for panicking when you are caught in the streets all alone with no friend in sight, rules for losing an eye or breaking a limb or even being sold to the slave fighting pits. If I flipped through the Mordheim rulebook again and found a rule for slipping on the bloodstained cobblestone after beating an enemy's head in, I would not be terribly surprised. In this new game, however, it is just red pieces vs black pieces. All factions and all moves basically work the same, with very little in the way of thematic rules (perhaps with the exception of the rather silly rules for the special characters, where you have to say something ridiculous at the table to get a small bonus). Rolling the dice and pushing the little men around the table doesn't evoke a gritty (or even half-believable) setting.
In addition to the missing thematic elements, the game mechanics are missing the details ("rules crunch") that would put limitations and strictures upon a player. In Warhammer 3rd Edition, for example, you can only wheel in a certain way, and must pass tests to reform or take turns. The result of this delicate maneuvering is that the battlefield becomes a place of intricate movements and counter-movements. Inevitably, units fail to complete their wheels or turns, leaving them caught in the middle in a terrible position, with the enemy outside of the frontal arc of vision and with flanks threatened. These are limitations that constrain a player's ability to have full control over his or her army, not merely as a factor of dice rolls, but as a factor of their strategy. A good general will not be caught in a position where they have to make overly complicated maneuvers—a good general will force overly complicated maneuvers on their beleaguered opponent! The new game throws such possibilities out the window in favour of a big scrum in the middle of the table.
I think these things make it mechanically a bad game, although, again, there are a ton of people out there that wouldn't mind this at all. A lot of people find chess pretentious (let alone chess with nerdy little elves and goblins) and find checkers to be a better way to spend their time with friends. For that crowd, the spirit of the game is enough. I think those players who want something a little more mechanically stimulating will never be satisfied with this game.
Again, this is all fairly academic. I don't plan on playing this game any. It is just fun to compare it to the best of old Warhammer (3rd edition, in my opinion) and see how very different it is. The other gripes people might have with the rules go into specific concerns that are beyond these general remarks—complaints about the new setting, for example, or the lack of historical influences.