It provides response formats: xml, json, csv, newline separated, serialized php. And enforce a limit of 240 requests per minute (that's 14,400 per hour for the lazy).
Fun fact, if you're running tor (tor-0.2.4.17 as proxy not the browser) you'll see the tor exit node in "IP:" and your actual ip i "Real IP:", thanks to gdns' EDNS (https://gdns.re/edns-demo/)