Just thinking about the rumoured Grav weapons mentioned on the front page. How does it work against models that do not have any armour save at all - i.e. Daemons that only have an invulnerable save? Does it still wound them on a 6, or is it unable to wound them at all?
Looks like the Grav weapon is a Plasma gun without the overheat problems, designed to take out the heavy hitters like the new MCs, Terminators, Obliterators/Mutilators, and even be able to take out all those hard to kill units like Nurgle Bikers, etc.
Form what I have heard, it is in limited number (does not replace the humble bolter), but is a specialist or heavy weapon, with the pistol possibly being an upgrade for elite infantry and HQs. It could damage vehicles regardless of their Armour value on a 6, and be almost useless against horde forces like Ork green tides, Eldar Guardian Footdar, Chaos Cultist horde forces, Imperial Guard infantry heavy Armies, and Tau that use predominately Kroot and units with low armour values, who rely on cover saves and shroud. Space Marine armies could begin to look like massed scout armies with camo cloaks, and characters to boost their cover saves.
Oh well this is all just based on rumours, and we know not to take them as real until we see it in front of our faces. Also if true, it forces gamers to build more balanced armies to cope with them. Add to this the sudden advantage SMs get with 2 new Anti-flier vehicles, Flakk missiles, and their 2 fliers, they are almost guaranteed air superiority. Then you add in their Terminators, drop pods, and other regular nasty units, and add to this the now rumoured cheaper space marine tactical squads, and you have a very powerful army.
It makes me wish that Codex Chaos Marines was released about this time, so we got a few of the really good things. Maybe some thing similar to a Psychic hood that Librarians get, but for Tzeentch Sorcerers, and Khorne Collars for MoK unit champions and ICs. Maybe the Mutilators would be replaced by something similar to a dread knight, or a Wraith Knight with a few nice little abilities such as wings huge invul saves, etc. Who knows, but being first off the shelf when it comes to being the new codex off the block , sometimes (well usually) means you do not get rules as good as those that come later.