I love my Kinesis Advantage 2 and would never describe it as old fashioned! If anything it has a look that follows it’s function and happens to not look like the sleekest thing. But one should not look at the keyboard anyway. :P
I used Kinesis keyboards for years, and preferred them over all others I tried... but for the price, the build quality was just atrocious. Went through several of them. Have they improved at all? For $300+ I expect something that feels rock solid and lasts for years, not the plasticky stuff that eventually broke (out of warranty, of course).
I discovered revently that the Kinesis was featured in the background of the film Men in Black, as a futuristic keyboard. The prop department had painted it black and the wave of consumer demand was the reason for them introducing a black version, like the one I have.