IG & the new Vehicle Rules
Strength 4 defensive weapons proved to be the annoying change that it promised to be. I was frustrated that I couldn't use my Hellhound's Heavy Bolter in combination with the Inferno Cannon, as I used to be able to. I think the 'Chimera rush' may be a new tactic, moving your armored elements forward as far as possible on the first turn, popping smoke then becoming a static firebase for the rest of the game. Strength 4 was however counterbalanced to an extent by the new blast template rules. I found my heavy ordnance to be much accurate on the whole. The real icing on the cake is the fact that there is no longer a penalty for moving and firing your battlecannons etc. This means that while Chimeras etc. may become more static, the Leaman Russ (or even a direct fire Basilisk) now has no real reason to stay still. Combined with the fact that armour 14 has become even harder to take down, the Russ & Demolisher have become better than ever.
IG & Run
Running is a surprisingly viable tactic for the 'static' guard, even in a gun line. Check my last battle report for a description of the guardsmen shuffle. In addition to this any last minute dash for the objective, or move away from a CC unit has been made easier. The only advice I have is to take Heavy Weapons out of your line squads so running becomes less of a trade off against fire power. With the increased amount of cover around, Fire Support and Anti-Tank squads should find it easier to hunker down somewhere safe.
IG & Indirect Fire
Indirect Fire is a godsend in high cover environments, as the shot is counted as coming from the center of the blast marker (thus negating most cover saves). This makes Basilisks even more devastating, there really is nowhere to hide. The lack of BS modifier on the scatter didn't seem to make much of a difference, but I may just have had some lucky rolls. Either way, I am strongly considering buying a Mortar squad, for the same reasons.
Close Combat & Rear Armour
This is going to be real issue for the Guard, those armour 14 tanks look less mighty when faced with a Carnifex in combat. However, I really think this is how it should be, and it will prompt some interesting tactical decisions, so its all to the good in my opinion.
So there are some of my thoughts, nothing earth shattering but some stuff worth noting for any treadheads out there. Enjoy...