There's an old adage in software, "if it's not broken, don't fix it".
So one has to ask, why are you changing an interface, that pretty well everyone who uses this site knows how to, navigate around, find stuff, purchase stuff, look at art etc etc ...?
The biggest complaint I know of in the current interface is the color. That would have been an easy fix with a few re-designed CSS files, especially as one of them could use a black background. Typically what people like to use to look at photographs. But you could easily have supplied 5 or 6 different color schemes that would probably have satisfied 90% of your user base.
I turned on Eclipse for the first time, tried to use it and was so under-impressed that I turned it off. It's marked as BETA, but in no way is this BETA software, BETA software has all the features that are intended for release "1", and used for full system tests.
If you ask me, this should not even be turned on for an ALPHA test.
Having been in the software industry my entire working carrier there's one thing that happens that will cause major upsets, and that's changing an interface, especially one that's simple to learn, and actually functions correctly.
And as a closing thought, why do I want my PC to look like a cell phone App?
Keep it simple, keep it clean ... wait a moment, you've already achieved that.
Turn this on full time, I will be leaving. There are lots of sites that accomplish exactly what you have today.