It doesnt matter if you start on a negative note.
I dont want to start one because many of my posts on here make me look like an xbox fanboy. If the game is good, it will carry through any negativity so give it your best shot no matter what.
As for Gears SP vs MP, I think Horde is great and its PvE like the Campaign, but it used to take 2-3 hours to finish and I stopped playing it for that reason, plus people in matchmaking leaving or not carrying their weights was a total pain in the ass. You dont have to level up the skill cards in 5, they level up with the Power you pick up, and the cards themselves are found in Supply Drops which you get 1 of for each 1 minute played in Versus. Or something like that. So there shouldnt be any problem with people not having the skill cards to perform well. I played a lot of Horde now in August as I was doing the Road to Gears 5 achievements and I had both people who dropped out when the shit got tough, but more of good players who really wanted to finish the waves and made sure to res others and all that - playing like a team. The new Escape mode in 5 looks like a shorter, modified version of Horde, the videos I have seen of it the run out lasts around 15 minutes.
I loved the social playlists of Versus in 4, but I will probably avoid Ranked matches again. I tried a couple of them recently, won one and lost one, and after the loss I got some borderline abuse messages from one of the others on the team over Xbox Live. I think they chuck the new players into other higher ranked games to see how you do and then place you in a bracket accordingly? I can understand why that can be frustrating and possibly lead to demotion, but I think I had my fill of that. Unless I git gud at wall bouncing with the Gnasher I dont think I will bother.
But I completely disagree with you on the main characters being bland, I have really enjoyed their company so far and having played through 1-3 recently as well I cant wait to see what happens next. In that sense Im excited for Gears 5 much like I am excited for a new season of The Wire or The Walking Dead. You know some shit is going to happen to some of the characters, its all a matter of playing the series out and see who it is this time.