I am a Simplenote user too, and loved it. But like you said, their iPhone app is too simple to use. Besides, I am not a fan of single window solution on the Mac. So I build this app.
Currently the only way to connect your Simplenote data from Note is by importing the data you exported from your Simplenote account in JSON format.
@king_magic Thanks for your feedback and suggestions. I love your idea about command line noting, and I will try to build one :)
For the syncing issues, I will check on that. iCould sync is a little bit confused: sometimes it synced in seconds, sometimes it just take a long time ... Anyway, I will focus on the sync issues in next updates.