Nice, even an endpoint that provides an iCal formatted version of the data 
However, the timezone IDs seem a bit weird for iCal (as in, quick testing with some parsers didn’t have 100% success rate), though I understand iCal doesn’t actually specify timezone IDs that clients should understand…
Edit: filed a uservoice on the timezones: Don't prefix iCal Timezones with / for better compatibility – Twitch UserVoice