I can only give you my thoughts on the SP, like in the other thread.
It was...good? I gotta say, I´m really not a Gears Fan at all, I think the universe is rather bland and unfinished but what can I expect from a shooter.
Still, I like what they do with those few ressources. The gameplay is solid, the enviroments are great...all the stuff that happens in the first 3 hours of play is commendable. I also liked the arsenal better than in the other 2 Gears, I had a hard time deciding which Assault Rifle to use most of the time, they all have their advantages
All in all, the SP is a really pleasant ride with very few boring or really frustrating moments. A step up from Gears 2 imo.
But there are also some things I really didn´t like, namely the whole ending which I of course won´t spoil, but I was really really pissed at Epic for that.
Concerning the other modes...I won´t play competitive MP but Horde and Beast seem like fun so far