The shadows coming from the elements are wrong. They're too dark and in the wrong direction (look at any normal PureBD GUI).
Also, Sphax never indents arrows, etc. on GUIs, but I guess this just depends on the style you're attempting to achieve on machines.
Last I recall watching Sparkst3r's videos I'm sure he said he was doing them wrong
Also, from what I use for GUIs (and have compared closely to Sphax's stuff):
- Drop Shadows from light elements are: #614B2B, 40% opacity, 106 Angle, 4 length (maybe 5 length)
- Elements like arrows that go on the wood backgrounds, etc. are: #614B2B, 50% opacity
- Elements like arrows as above, but when active for progress are: #322817, 85% opacity
[these are close approximations, obviously I can't know
without seeing Sphax's PSDs, but they match pretty closely]