Rough Collies here - many of them, over many years. All are different personalities within a very similar breed type framework, so below is generalisation.
They are a breed that is very out of favour these days, probably in no small measure due to vets' insistence that dogs must be neutered - does the coat no favours at all, and can make it very difficult to maintain. They are generally an easy to live with breed, and I always recommend that people do not neuter unless medically necessary. They certainly draw a lot of attention and nostalgia when out walking, so it's a shame people feel they can't cope with them now.
Breed stereotype - loyal family dogs, yep. Can be a bit gobby if allowed. Not the 'herdiest' of sheepdogs, some more prone than others but not known one be troublesome with it as some Borders can be.
Pros: Very easy-going dogs who will take as much or as little exercise as most care to give (obviously all dogs need daily exercise, but they're not likely to be climbing the walls if you have to miss it or cut it short for a day in a crisis).
Intelligent, but not in a challenging way. Very easy to walk - not confrontational with other dogs, and generally obedient, no strong prey drive in most.
Cons: Well, obviously am not going to claim they are low maintenance - the coat does need some care, but choose a breeder who has sensible coats and they are not difficult - an hour a week will keep on top of it. There will obviously be a bit of hair around the house though.
Some can be a bit wimpy, particularly around floor surfaces. As with all breeds, choose a breeder carefully for temperament and one who does not breed for excessive coat.
Much of the nostalgia you meet on the streets hangs around a past era of dogs with a bit more size and a bit less coat - there are breeders out there who have this, there are others who have much smaller and prettier - but in these internet days, it's easy to work out who is who.