I like Ada a lot, and I've been known to push it, only half-way kidding, on many occasions. However, there are a few things that make the language somewhat annoying to use, especially for someone who is accustomed other up-to-date languages (Python, C++11, Java, Scala, etc.). The obvious one is probably the verbose syntax, but really I don't mind it too terribly much (writing "function bah return integer is begin .... end blah" does get a little old though). Here's a list:

* No type inference. The lack of type inference means that I end up typing the names of types all over the place (or renaming them to be short, which doesn't really help the reader much).

* No lambdas or closures. I really want to be able use higher-order functions, but Ada makes that difficult.

* Extremely verbose generics. Ada has amazing support for generics, but there's so much overhead to use them (syntacticly) that I usually avoid them.

* Strange dispatch syntax. I personally like it, but it is strange to those more accustomed to C++ or Java, where methods are part of the class. In Ada, methods are declared as taking a "tagged" type as a parameter. Related to this, I really think Ada should support multiple dispatch (if you're going to have the strange syntax, why not?).