In one sentence, this Naldo is a fantastic free card, but he is probably a bit too clumsy, slow, and awkward to be an effective CDM.
Starting with the positives, his tackling and physical presence at the CDM position is exceptional. Like many other tall players, he has the ability to stick out a long leg and recover the ball in lots of situations. His positioning is exactly what you would expect with a M/M card; he doesn't move around too much and generally follows player instructions. At 6'6", he is very good in the air, but the low jumping lets him down in certain situations; he's not a massive threat from set pieces which surprised me a lot. His passing is acceptable for a CDM, and the 4* WF is a nice bonus. He is certainly able to take powerful shots from range, but I don't think it would be worthwhile putting Naldo in an attacking position.
The three big negatives with this card are the pace, the general clumsiness, and the poor stamina. He is easily dribbled past by quick players (and even some not-so-quick players) and he really lacks the boost of acceleration often required to actually put a tackle in. In general, he is very clumsy and awkward in tight situations, probably due to the low balance. Finally, as I like to chase down attackers using my CDM, the stamina is a bit of a problem if you have a similar play style.
Overall, it was a fun card to use and you can't beat the price (free) even if the card has some major problems. In terms of feel, I would compare him to Rijkaard and David Luiz, although I don't think this Naldo card is quite on their level.
4* Weak Foot