For anyone who's on the fence about whether or not you should do the FUT Birthday Ramos SBC, I'd like to give you some feedback regarding how he performs in game and hopefully that will help make up your mind one way or the other, I'll try to be as objective as possible and look at the good and bad.
What's good about him
To nobody's surprise, this card is aggressive, by the time the ball reaches the attacker he is instantly on them, that aggression make him feel faster than he is.
He's very good in the air with excellent positioning and jumping, his attacking headers are very impressive and have no trouble winning defensive ones.
He is also quite agile relatively speaking, I've had to no trouble keeping up with nimble attackers and his Reaction is incredible, he will block and intercept anything that comes near him.
His tackling is also very strong as he tend to leave the opponent on the floor after winning the ball which reduces the chance of an unlucky bounce. Very impressive both with his physicality and defensive skills.
What's not so great
So there's a few things to note when using Ramos, none of them breaks this card but it may take some getting used to.
First of all, due to a combination of his H/M workrate, high Aggression and Attacking Positioning, he does tend to push further forward, this is actually more obvious if you play a low defense line as he could stand 5 or even 10 yards ahead of the other CB, however this is less obvious if you play a high line, I think he would really suits somone who wants to play a 70+ defense line.
Secondly due to this tendency to push forward, Ramos is not quite fast enough to recover if the opponent gets in behind him, his pace would be fine for other centrebacks but for someone who likes to defend on the front foot and actively make tackles, if he misses one near the halfway line then there could be loads of space behind him.
And I did find that he does miss the tackles a bit more than others, this is probably due to him reacting so quickly to a situation and jumps into a tackle very quickly, so quick that sometimes if the opponent just make a first touch in another direction he could miss it completely.
Also compare to some of the taller defenders, when he's grappling with a taller striker he does have touble getting his foot in at times, although if you just stand your ground his reaction is so good they won't be able to shoot or pass through him.
I think Ramos is very very good defender, defensively speaking he is right up there amongst the best, but it's really his attacking tendencies that could potentially catch you out. It's not something you can't deal with because he can win balls much higher up the field for you, and he does have good passing and dribbling to help launch a counter for you. So there's pros and cons to his game.
Although I will say, I don't think he will be an endgame card like in previous versions, if he had 90 Pace that may be a difference story, but as things stand, he's not quite as good as the truly top tier defenders like TOTY Marquinhos or PIM Maldini, and I can only imagine there will be even more cards that surpasses him come TOTS.
As for whether or not you should do the SBC, I think if you are still using someone like a WW Cozza or SD Pique, then he is an improvement, good enough to comfortably last you until TOTS, which granted isn't that far away. But if you already a good CBs you are happy with, unless you really have just too many fodders that's burning a hole in your pocket, I would leave it and see what else comes up.