I am a complete amateur who wanted to improve my photography skills. I joined gurushots sometime ago and it has helped me enormously. There are some great photographers and photos posted and you can generally see the settings these were taken at. When you post photos you get and overview of whether they are a strong, very strong or average image. Viewing and voting on other peoples photos has improved my composition and eye no end.
The voting system is not foolproof especially in the speed sections and yes you can spend some money buying keys and fills but nothing comes for free.
I reiterate I give it 5 stars for improving your photography!