Gears E-Day is probably the best Gears game, hands down, in terms of gameplay and overall feel. It easily trumps 3's Horde mode with the new Horde Siege mode.
That being said, you are approaching a game caught in a weird place; there is a ton of misinformation on both the right and left sides.
The fault of this is entirely the writer who tried to force modern politics into the game. That being said, after beating the game, it seems that management muzzled him, so much so that he lamented about not being able to do more on Social.
This is Starship Troopers The Movie, the writers intentions were bad, but the execution was good. Mags character is at worst, mildly annoying. The game primarily focuses on Dom, and Marcus in that order, Reyes was a good character, and the addition of Zee the Carmine Patriarch was solid, Tai and his squad get about as much character development as Mags.
That being said, Intention is sin in of itself. People should be calling for the writer to be fired. E-Day is solid, and it stands next to Gears 2 for me in terms of story. It was very much a story that Gears needs more of, gritty dark, the Trauma here is good build up for Marcus and Doms relationship, and Doms family.. You can really see the pain beginning to build, which punctuates 2 much better than Gears 1.
Though to be fair Gears 1, was kind of hap hazard before they realized they had a franchise in the making so the characters there are very plankish compared to two or E-Day.
I'm just glad they didn't do what they did in 3 and change it to lighthearted, especially considering, ya know, everything that happens in three.
Playing GoW E Day and quite enjoying it so far, open any discussion, its american culture war