Ralph Johnson has praise for Erlang.
Erlang is going to be a very important language. It could be the next Java. Its main problem is that there is no big company behind it. Instead, it is being pushed as an open source project. Its main advantage is that it is perfectly suited for the multi-core, web services future. In fact, it is the ONLY mature, rock-solid language that is suitable for writing highly scalable systems to run on multicore machines.
He cites the USP of Erlang is not its functional programming style, but its ability to make most of multi-core machines. Most of the popular languages are caught without explicit support for the new hardware developments, which will drive the future of programming. Erlang, with its, explicit intent of concurrent programming is the most probably to fill in the gap.
Ralph Johnson also plays down the hype around functional programming. He builds analogies between processes and objects, a OOP guru that he is, and how they achieve the same purpose. As a C++ fan and a programmer with majority of OOP experience, I can say that my initial learning experience with Erlang is along the same lines. But that suffices only the abstract view, to find out similarities and differences, to know what to reuse and what to unlearn from your past. To be able to dive into Erlang, one has to embrace functional programming completely. The biggest deviation here is not from OOP, it is from imperative programming.
I can definitely say that OOP concepts have helped me in understanding Erlang, but it is a matter of how they are applied for learning. It might not be true for everyone. LtU has a good on-going discussion on this.