Thanks for the critique, duly noted. Critique is almost always more constructive than praises 
But I’ll have to correct/tackle some issues you raised…
It’s exactly that, a beginning. Most of the time went to building the editor, not the actual styles. And…
That’s exactly my goal: a complete theme, with multiple different styles for some of the components (not all, for starters at least). Try not to judge the completeness just yet 
This is where I disagree completely. As I see it, the “simple” part refers mostly to the actual implementation: the CSS. The “functional” part then refers to the actual look and feel of the theme.
Functional does not mean it has to be ugly (but neither does “imageless” and “gradientless”, I’ll give you that), quite the opposite. With functional, I strive mostly for “usable”, but that’s a though goal to tackle with a simple theme alone, so my weapons are quite limited. Hence, using a few well selected gradients will hugely benefit the overall usability and affordance of the theme. With the words of Stephen P. Anderson:
I encourage you to read his article,
In Defence Of Eye Candy
, and look at the slides
on his website
. There’s even scientific evidence to justify the use of gradients
And aren’t you indirectly saying OS X’s theme isn’t functional? I hope that’s not what you mean to say.
Again, I disagree.
Do websites need to look exactly the same in every browser?
No. Small differences will do no harm, and lowering the bar because of lesser browser makes no sense to me. And to quote another well respected web professional:
Only web desingners and developers look at websites/webapps with two different browsers to see if they differ. We musn’t promise end users pixel perfect results across all browsers, which is impossible for many reasons. And that’s why
we should stop showing static visuals to clients
(I’m still guilty of this, but slowly working towards a different working process). So why lower the visual/usability bar on all browsers just because few of them fail to render one aspect of the design that will not ruin the overall experience (because they’re not knowing something’s missing)?
See for yourself, Google uses gradients and rounded corners, I dare you
Now, I think my theme tester might be a bit misleading in it’s presentations currently, when the “alternate” color is used so prominently. But the idea of course with the “default” buttons is that you use them sparingly, i.e. only one such button per screen. Same goes for all the more prominent styles in the theme. But I’ll be tweaking the colors, borders, spacings etc. next week.
Now things start to fall more into the personal tastes category, but I’ll bite it: I think Google Maps looks really good, largely due to the good looking maps themselves, but in general the controls are polished. Still, I’ll take a dozen
github’s
before
googlecode’s
, but I’m sure it’s just a personal preference not applicaple to everyone