Any form of critique is a valuable tool.....I have reservations about paid critiques......I ask myself the motives and qualifications of the critiquers and the quality and honesty of the critique can sometimes be suspect.....but that aside if people benefit from them ...great.
It depends on the type of song and the resons for writing it..... for example a song aimed at the commercial market has to slot into the requirements therefore a critique from a succesful commercial writer can be a good thing.
On the flip side the same person critiquing a song written for fun and for non commercial purposes would probably give a critique that was irrelevant for that type of song.