Oh noes... Well witholding judgement till I can give it a try myself, but Halo 3 was by far the best online multiplayer experience I had. Reach could have been, should have been, but I think the forge let it down sadly...not the features, just most maps looked the same and you couldnt quite re-create the awesome custom maps/game types you could previously.
H4 just completely dropped the ball for me, not so much of a focus on forge/custom games, limited playlists..(Which just comes across as cheap for me for arguably Xbox's biggest exclusive). Personally I was fine with the perks and etc., but perhaps it did take away from Halo's spirit.. Think lack of vehicle combat was greatly missed for me too.
If ADS really feels great in Halo, I'll support it, but I have been fearing this since 343 got Halo. "How long till they try making Halo more like COD", they should hope its worth it.