Hi there!
Personally, I think Winter whites are lovely little animals, but as souffle said, it depends on where you get them from. Some pet shops may have WW on the tank, but what's inside the tank may not be purely that. You have to be careful about your sources, so you are prepared in the long run - hybrids unfortunately get the cons from both Russian species, including the Diabetes risk from the Campbell genes.
Of the two Russian dwarf species, I would say WW are often the more friendly. You will often find that Campbells will be more tolerant of their own kind, and less likely to need to be split up, but can get a little impatient when being handled (unfortunately they have a reputation for being nippy, which is often very unjustified). Winter whites on the other hand are a bit more irritable with their cage mates, and more likely to squabble, but are a lot better for handling.
I work in a pet shop and we sell Winter whites. I get to briefly handle them when I fill up food and water and do quick health checks, and it's rare that I get an aggressive or jumpy one (unlike the often aggressive, flighty, screaming syrians haha). They are normally very patient when it comes to handling, and I don't think I've ever been bitten by one. And they are so funny and charming.