When SBC FFS De Jong came out, I immediately knew I had to do him. I struggled fitting him in my side until weeks later after multiple weekend league when I saved up for FFS De Ligt. Having loved both of them, I knew I had to do Haps. He cost me 92k after all was done (using untradables, selling packed players). I don't regret it in the slightest. He is the best LB I've used in Fifa 19, and I've used RTTF Tagliafico, Telles, Alba, Marcelo, Sandro, IF Robertson, and more.
Pace- He is ridiculously fast. 90 acceleration to go with 91 agility and 87 balance, not to mention 97(!) sprint speed. He is constantly running up and down the pitch and he can catch up to any attacker on the game.
Defending- He is a very skilled defender, not very tall or strong but tactically very solid. He marks well and makes good tackles.
Passing- Good short passing to midfielder and other defenders. he can start up counter attacks very well wit his short passing (88). He is great at whipping balls in as well with 94 crossing.
Physical- (With Sentinel) He has 83 strength which isn't much but does the trick and is made up for by his pace. He has good jumping and aggression, but this is nothing compared to his 99 stamina, the stat that really puts him over the top. With 94 pace, 91 agility and 99 stamina, there isn't a moment in 0-120 minutes that he isn't the fastest player on the pitch.
Work Rates- This is a personal preference, but I prefer my fullbacks with High/Medium and I put them on stay back while attacking.
Haven't truly noticed any, maybe some people prefer fullbacks around 5'11" or with High/High, but to me there are no flaws.