We struggled to use Talent.io when I was recruiting developers for my past company, which I think can mainly be chalked up to our high standard of candidate needed.
It seemed as if many of the technical candidates on Talent.io are either self-taught or recent graduates from one of the many bootcamps (code academy, general assembly, etc.) which is fine if you have the ability to train to them slightly more when they first join. We didn't and the majority of candidates failed our initial technical test.
On the plus side, the site is easy to search through and find people that fit your criteria so it was never much of a hassle even if we never quite found someone suitable.
I imagine that if you are looking for a junior developer that you can take time to train, then you would find this site much more effective for you.