I installed mine on the weekend.

First up, I was pretty surprised how easy it was to install.
I bought mine second hand off Ebay, and it didnt come with an instruction manual.
When I first opened the package and saw all the wires, my first thought was "Oh faaark" .

The install guide was readily available on Cranes website though, and basically involved tapping the HI-6 into the coil, and giving it earth and power.

Hardest part of the install was finding a spot to mount it (decided on glovebox, thanks ebs_4l for the idea), and then running cable through the firewall
I'm a spastic with anything wire related (plus I take alot of smoke breaks ), and I had the whole thing installed, working, and wires neatly crimped, taped and cable tied in an afternoon.

Car is an ED XR8 Sprint, with genie extractors and a single 2.5" exhaust.
I replaced my dissy cap and rotor before installing it (bosch items), leads are bosch spiral coil (looking for something a bit better/better looking), plugs are recommended NGKs.

I'm still running stock coil with it ATM (ordering PS92 coil), but it has definately made a slight difference as it is.
Cold starts are definately quicker.
It appears to rev a a bit cleaner throughout the rev range.
Also got rid of a slight 'stumble' the car had when being a bit clumsy with the pedal at low revs in a high gear.
Above could also be related to new dizzy cap and rotor though, though my old ones didn't seem stuffed.
If the car was staying this stock, I might not have bothered with it to be honest though.

Negatives?
The fact that all the cables are hardwired to the unit.
Because I'm not using the optical input, retard control, the stage rev limit switch, or the cylinder select (open for 8s, earth for 6s, 12v for 4s), it means I have a bunch of cable behind my glovebox.
Not much room back there
And if I cut them off short, it'd be a pain if I ever wanted to sell it, or use it for something else.

Also, the unit makes a bit of noise.
Think invertor switching on and off really quickly.
Can't hear it anything above idle, but if you are keen on interior silence, or dont want passengers asking "WTF is that?", I'd try and mount it in the engine bay.

Hope thats helpful to people who may be umming and aahing about it.
I know I was, mainly because they aren't really that common, and I thought it would be ALOT harder to install.