I used the Gatwick North, No 1 Lounge the other day, early on a Monday morning. Despite having read that it's often busy and may turn Priority Pass holders away later in the day, I have to say that I found it a good place to wait for my flight at that time There was some relatively comfortable seating, a choice of breakfast food and drinks, and in one part of the lounge the lighting was subdued - particularly helpful as I found the neon lighting elsewhere in the airport quite harsh at that time of the morning.
I still haven't been, but the No1 lounges do look pretty good. However, I think my judgement on lounges is probably quite suspect at the moment, given that I genuinely enjoyed the food, service and ambiance at one of the Manchester ones last month! (Usually, they're pretty bad - assuming you can get in. I was turned away with Priority Pass 3 times in a row last year).
Yeh, I think it must have improved (certainly the food), sometime during that period where I couldn't get in. As I say, last time I went, I was genuinely quite impressed.
If the No1 North is at all similar to the No1 South, I'd certainly consider it a pleasant way to spend a couple of hours waiting for my flight.