I hate to even out the voting, but I've got the BT555U (it's been replaced by the BT558U, but they're very similar) and I love it. It's got a ton of nice features for the price (3 2.5v preouts), Bluetooth, SiriusXM readiness, ability to make and recover calls, voice control, ipod, Spotify, pandora control, etc.) and as far as shininess goes, it changes colors! There are 24 presets, one that slowly fades through them all, and the ability to definite custom colors with rgb values.
Navigation isn't the easiest, but only during initial setup. There's one button to cycle through the sources and the only real difficult part is navigating the settings menus on the fly, which you shouldn't be doing too often. The only time I ever really do that is for the EQ presets and you can get there by pressing in the wheel twice, going right three times with the wheel, a pressing it in again.