I have the J-Station and love it. The website is still operational and you can download the software and presets. To get the most out of the unit, I strongly suggest hooking it up to your computer. The ease of deep editing increases greatly. The interface is like a rack system with a compressor/gate/delay/reverb/wah that you can use simultaneously and a menu of effects that you can use one at a time (phaser/flange/chorus/pitch/trem/rotary).
As stated, the coolest feature is the ability to combine heads with cabinets for an almost infinte number of sounds. You even get a few bass amp models for when you need them.
As you can tell, I am a fan. Check out the J-station user group on myspace for some clips.