Career mode is absolutely playable - just relax during games and enjoy the good times and bad times.
Sliders do work as well. I'm currently using one of the older versions of gonira's current-gen sliders. I think I kept man marking to 48 for Hum & CPU since it gives me space to score beautiful goals, just a preference.
The experience has been absolutely perfect. I'm using Man Utd and my transfers have been the following:
IN:
Ravel Morrison
Marco Reus (got him for Nani + 20m)
Ryan Gauld
Fabio Coentrao
OUT:
Alex Buttner and many deadweight (ie youth players whose rating were too low to progress like Larnell Cole, Will Keane -- I kept Lingard, etc)
So far, I've had brilliant games. My opening game against Swansea started out 2-0, with me conceding two goals in the opening 12 minutes. I then dominated the rest of the half with no goals to show for it. The 2nd half was an absolute onslaught as I managed to grab 5 goals. Headers from RvP, Carrick, and Fellaini and two well-taken goals by Reus.
I've lost twice this season and both were games wherein I felt that I could've won if I had more luck. (2-3 to Shaktar thanks to Bernard's brace, I was already up 2-0 courtesy of Welbeck and Young; 0-1 to Liverpool at Anfield thanks to King Suarez's godly goal)
So just take it easy and relax. Enjoy it! If it helps, I'm also using Krebstar's CTT and I think it gives gameplay a much needed variety. Liverpool and Swansea both killed me with their possession play. (My goals against Swansea were: 3 from counters, 2 from corners)
I think the best match I've played so far was against Man City. I took the lead with Wayne Rooney's poacher goal. Joe Hart mishandled the first shot which he should've easily caught and it deflected off Thiago Silva which I gratefully dispatched to an empty net. Then it was RvP's brilliance for the second. City then had their customary comeback through Jovetic and an Aguero penalty thanks to my stupid bump on Silva on the edge of the box. I then went on to snatch victory at the death through a Marco Reus goal off a rebound. Beautiful stuff.
I think that the main difference between great and subpar teams is the fact that great teams pounce on every error you commit. Jovetic's goal was through a single error while the others goals I conceded from poorer teams were simply my poor defending costing me. (or it might've been the very slow Rio)
Note: I also have other CMs like AC Milan, PSG, Madrid, BVB (they are my teams for the major leagues) and they have been ok as well.
I play 10 minute halves with all-manual settings. All-manual takes some time to get used to and it's annoying when you misplace your passes but I honestly feel that it should be part of the game wherein supposedly easy passes are also misplaced due to your error as a player in aiming. It also sucks when you're 1-on-1 against the keeper and you place the shot wide. Yet it makes the goals and key passes all the more fulfilling to pull off. You really have to play to your team's strengths. In my Dortmund CM, I rarely use wing play and dominate teams through the center of the park. In my Madrid CM, Bale, Isco, and Ronaldo wreak havoc every single time. For PSG, Zlatan's hold-up play is King. For AC Milan, I purchased Yaya Toure to have the ultimate box-to-box CM. For Utd, most of my goals come through the counter as RvP and Rooney are extremely lethal. Reus isn't half-bad either as his quickness and finishing are pretty good.