Any thought on using a Z90 for interviews?

Looks like any of the small LED lights. Probably get what you pay for. If you were short on money and setup time, and didn't mind a small reduction in overall quality, I'd use it.

edit:

HOLY CRAP THEY'RE A THOUSAND DOLLARS?

I think I'd pass in favor of any of the $50 LED lights that have been mentioned here recently, or sink your $1k into an Arri kit and get some "real" lights.

Any thought on using a Z90 for interviews?

The Z90 is an amazing light but I'm trying to fathom how you intend to use it for an interview. If it's for walkups outdoors on top of a shoulder mount camera then it's ideal, we've sold quite a few to the ENG guys. Indoor sit down interviews, well it sure would be handy to have in the kit but not as your only light unless you just want it for fill. The plus is you can match it to anything.

We use the Z90 as a backwash light or lighting a background. It is too uneven and a little hot in the center
for a key light in my opinion. I would use it as an interview light only in an emergency only.

I own a Z90 and an IS3 (Zylight's large panel light).

The Zylights are some of the most sophisticated units on the market today, hence the high price tag. What makes these lights different are that they have more controllable output than another unit available.

All but the cheapest LED lights are dimmable; the Zylights do that.
The better LED lights (Litepanel Bicolor) allow you to dial in the desired color temperature; cheaper ones require gelling like traditional lights. The Zylights have instant 3200 and 5600 mode while also offering precise dialable color temperatures from 2500 to 9000 degrees kelvin, with numeric readout.
In addition, the Zylights have dialable green/magenta shift, fantastic if you are having to balance under standard fluorescent or sodium discharge parking lot lights etc.
And finally, they have a color mode, where you can dial in a specific hue and saturation of any color in the spectrum, for "party gel" effects.
You can save two looks via preset buttons.

All of these functions are available via the rear panel, however Zylight also makes a remote that looks similar to the back panel of the Z90. With this you can control every function of each of your units, up to 11 at one time. So you can stand at the monitor and tweak the intensity, color temperature, green/magenta shift or the various functions of color mode. I can't begin to tell you how great this functionality is and how much time it saves.

For an interview situation, I use the IS3 as a key or fill and the Z90 as a hairlight. Usually in these situations, you set up the lights as best you can with either nobody or a stand-in of some sort and then do final tweaks when the "realie" arrives. Obviously it's best to get said tweaks done as quickly as possible. In a situation where the interview is standing, for instance, the lights will be high enough to require standing on something to be able to get at them. So now you are pulling in a chair or a stepstool or a ladder to make alterations to the units, particularly the hairlight.

With the Zylight setup, the second the subject gets into frame I can go to work on the remote, adjusting all the parameters instantly while watching the results. Blonde hair needs a little extra warmth from the backlight, but less output ? Done in seconds. Gent with ruddy Irish complexion? Cool down the key a little bit. I can make the adjustments in a tiny fraction of the time that I used to, and often with more subtlety than before. Unlike tungsten lights, where having units on dimmers would also shift the color temp, every function is discrete from the others. In a situation where multiple interviewees are being trotted through the setup one after another, the time savings is immediately apparent, especially the smaller the crew (i.e. one man band!). The few times I've used these lights in this way, I've heard exactly the same thing from the producer: "you're ready? really? Wow!"

So yes, the Z90 works well as a backlight or hairlight but I wouldn't use it as a key light--the IS3 is the better unit for that. In any event, I bring these on all of my jobs--they have been integral to many high-end music videos, commercials and episodic TV jobs--and they never cease to impress the gaffers I work with. If I sound enthusiastic, it's because I am--this is some of my favorite gear.

The next item to emerge from Zylight was something that approached science fiction--their Active Diffusion was a big crowd-pleaser at NAB. A flexible material (could be rolled up and transported in a tube) that can be dialed from transparent to opaque diffusion and anywhere inbetween via dimmer, powered by a 9v battery. This will be available soon for their various units, and will be controllable again from the remote. So I will get to add variable diffusion to the list of instantly adjustable parameters. Amazing. (video here (http://isquint.net/2010/nab2010-zylight-introduces-active-diffusion-lcd-panel/)).