I've stayed there - I'll give you a review.
Now keep in mind I'm a huge Disney snob. I don't like the idea of taking a Disney vacation and staying off site. But we LOVEEEEEEEED staying at the family suites!
We went in July 2003 - spent half a week at Pop Century and half a week at Holiday Inn Family Suites (now Nick hotel). We were miserable staying at Pop Century, moving over to Nick hotel was awesome.
Here's a comparision of Nick Hotel and Pop Century...
Nick Hotel - has it's own HUGE water park (free)
Pop Century - has regular pools
Nick Hotel - park right near your room, so coming and going is easy
Pop Century - park pretty far away, exhausting walking to and from the car
Nick Hotel & Pop Century - both about the same distance from all Disney attractions, both very convenient
Nick Hotel - TONS of space, couple bedrooms, living room, kitchen
Pop Century - Tiny room for all to share with no fridge or anything
Nick Hotel - free huge breakfast buffet each morning (at least there was in 2003)
Pop Century - pay a fortune for your breakfast each morning
Really, the only disadvantage I could think of for Nick Hotel was that you don't get the perks of staying onsite (extra magic hours and such). It was a really, really nice and fun place and I'd love to go back again.
I would definitely choose Nick over a Disney value or moderate resort, but I'd choose a deluxe Disney resort over Nick. It is very comparable to the value resorts as far as theming, but then it takes it up a notch by giving you more space, a waterpark, and free breakfast. And it's just plain nice at the end of a tiring day at the Disney park to just get out of your car and have a 2 second walk into your room, where at the Disney resorts you usually have to walk FOREVER to get to your room.
I LOVE Disney resorts, but I loved this place too. It was great and I recommend it to anyone with kids to try at least once. Even if just for a couple nights.