FP is an interesting language. In my opinion, it is somewhat problematic that different language concepts (Delphi, etc.) have been more or less merged into FP, resulting in redundant object models, for example. Pascal as a language also has various historical legacy issues (dangling else, block overhead, global namespace, etc.), which Wirth corrected in Modula and Oberon. The compiler is huge and apparently difficult…
That was not an FP invention, though. Delphi already did it - they kept the Apple's Object Pascal constructs from Turbo Pascal, and then bolted a whole new object system in parallel. FP inherited that mess and has to maintain it for backwards compatibility reasons. That said, given that the two systems are completely orthogonal, you can simply ignore the older one.
The biggest thing going in favor of FP is that it has been around for almost 30 years now, so it's very mature.