We had a few users suggest that the app could use a facelift but since it seems the majority of people prefer the way it currently looks, we're pulling that off of our to-do list.
Well to be honest, the GUI could probably do with some
minor tweaks. Of the 3 you showed, it's the most visually-appealing and Apple-like -- though it could maybe be a wee bit better. Now I'm talking MINOR tweaks, not a radical makeover. The things that bug me are the varying sizes, and more importantly the
spacing between all the elements. There's an iconsistency all over the place -- and the other two designs are
slightly better in that regard only. The good thing about the first design is that it has a lighter, airier feel and a nice use of some color. It also
feels like there are input buttons that you need to interact with, while the other two look bland and flat in comparison.
So design tweaks are definitely something you should do
eventually, but it's low-priority. If you have actual functional enhancements (rather than cosmetic enhancements) to work on, I would say concentrate on those elements
first, and then do some design tweaks later.