.io domain names

There are tons of niche.. 1 word domains available with .io extension, but i was wondering if they rank well in google? I see alot of startups using the .io domain names.. wondering if .io's are worth the time.

i know domain name effect on rank but if you have best quality unique content that's good for rank and index.
i will suggest you some point:-
Select Low competition keyword using Google Adwords
Work On page
Tag with image
Then start Off page.

that's good for rank in SERP.