Simplify the UI
The architecture of the app is exactly what I'm looking for — particularly the ability organize by tag/label — and I'm ready to switch from nvAlt and purchase your Pro version. But... the UI is clunky.
Open Sans is not a good font for small sizes and just bad for UI. It lacks the letter spacing/forms and spacing that Lucida Grande does. Some ideas: http://tinyurl.com/6yxoz4q
There's appears to be no option for picking a note font. Why? Again, Open Sans is not a good font here. When writing/coding allowing for user preference is critical.
The button sizes are inconsistent and distracting large (medium sized at the bottom, huge at the top). Do we need a giant sync button? I would make them much smaller and consistent.
Lastly, the logo in the upper-left is unnecessary and distracting. It adds nothing to the functionality of the app. I can think of no other app that does this. (You also might consider a logo redesign, but that's just me).
I hope my criticisms are not too harsh but part of what I love about nvAlt and Simplenote is the loyalty to speed and minimalism and you're so close to having a great app.
The logo is already gone, font options are in the to-do list now. The “giant” buttons will stay though, at least for a while :-)