Well if he is talking about the Pulsar N550 Digisight then I can give you my views as I have one myself.

For the price, I paid £995 which included the add on IR Illuminator I am delighted. Having not used traditional Gen1-3 scopes I cant really give a comparison with the DigiSight but in terms of practical application I have one on top of my .243 for foxes.
I was out with it a few nights ago at approx 23.30 and observed a fox clearly at about 450, it was admittedly a moonlit night. Called him in to 80 yards and finished the job.
Pluses :
Good value NV
Good recognition at distance
excelent clarity out to about 100-150 yards weather depending
Not prone to flare from outside light sources
Robust design
Simple "One Shot Zero". Fire a round, using the elevation and windage controls move reticle to bullet strike, press button, Zero complete
Minuses :
Fiddly controls. The focus knob is right at the front of the scope, so to adjust focus you need 6 foot long arms

Eats batteries. Expect to use 4 x AA per outing. I now have loads of 2800ma rechargeables
Not practical to spot with. In the same way as you wouldnt spot with your day scope dont try spotting with this. You need a seperate NV mon/binocular unless you have biceps the size of Bournmouth!
I would not call this a Day/Night scope by any stretch of the imagination. You "can" use it during the day to zero but its not an operational day scope.
All in all this is a perfect scope for what i use it for, sitting in pitch black, no visible light giving away a position to lamp shy foxes and good range and clarity.
If this isnt the scope your friend was asking about this review is probably irrelevant, but hopefully it may be of use to someone else.
ATB
Pat