I've been impressed with Gears 4, overall. The have to fix the Horde bug with the new (well to to Gears 4) Clocktower map and the Kestrel getting stuck inside a building. It seems like they're engaging with their community a lot and they're serious about improving the game and adding new content. I love the card skill system in Horde mode, though I feel they should add a passive bonus at "dead" levels, and add a "No Limits" card slot that lets you use a single skill from other classes.
For the social (non-competitive) aspect of PvP, this is really cool. Sure, it's highly likely that PC gamers will have a distinct edge over console gamers (higher framerates, better response time for peripherals, etc.), but for the social aspect it's great. In my case, for example, I have friends who play Overwatch, one on Xbox, one on PS4, and I play on PC. I would love to play with them, but being all on different platforms makes that impossible currently. I hope these trial-runs go well so that cross-platform play can become more of a norm.