A happy Cavalier mom right here....I have had Gus since he was seven weeks old--he is twelve years old right now. He loves everybody he meets (kids or adults, doesn't matter), loves to snuggle on the couch, loves being outside...sure, he's slowed down a little over the years, but he still likes to chase after the occasional squirrel. And he *almost* got a walleye for lunch at our cabin this summer

(I had taken it off the hook, it fell onto the dock before I could toss it back in the water...Gus was puttering around on the beach and I didn't think he noticed...boy, I've never seen an old dog move so fast

)
My own personal homily to the breed aside, I've met many other Cavalier owners over the year. All of the cavs have been great dogs. I've never heard of any that were nippy, or poorly mannered, or anything like that.
I've also heard of them being cross-bred to poodles (cavapoos? or something like that...) if you're concerned about the shedding. Personally, as long as Gus is groomed regularly, it's not a problem for me.
Good luck on your decision!