This is just my opinion, so if you are a fan of these shots please write your opinion!!!!!
Some players are using the Nadal shot as their main shot at the moment in online games, and they also use the dropshot with 100 or so points in it. I just find the overuse of both of these shots quite ridiculous. They are both overpowered in my opinion, especially the dropshot. The Nadal shot, while it's possible to return it rather easily, somehow makes it very hard to aim and time your shots well enough to cause problems for you opponent. When your opponent constantly hits it it makes you feel like your players feet sort of entangle more and more as the rally goes on, very effectively making you passive. Ok, perhaps I haven't had enough practice against it, but this is how I feel at the moment.
The constant use of the Nadal shot isn't nearly as bad as the use of the dropshot at around 100 points. It is way too difficult to catch these kind of dropshots imo. The opponent doesn't really even have to set up the dropshot, they can hit dropshot winners even if the other player is only slighty badly positioned.
I haven't tested the Nadal shot on faster surfaces, but I imagine it's less of a problem there due to the multiple buttons needed to hit it, but it's really annoying on slow surfaces, let alone ridiculously unrealistic. And I only mean the constant use of it. The main issue is the dropshot though, I wish it could be tweaked a little, just so that it would be more balanced.