I have just tried it to replace Pebbled, which was a fantastic job but not maintained too much anymore
and all I can say is waouh. That is really fantastic. I have also upgraded my watch to latest firmware (so I am probably positively biased because Pebble did a great job too...) but while I was expecting some glitches or worst, that went like a charm.
That is the great part of open source: when several people improve things hand in hand, from original source to forks and from authors to contributors and even testers!
I would happily give some free beers (as I did to smoku) if I ever find how to do it?

conclusion: thanks a lot