They are awesome. I love them. I have a Cardigan Corgi and also lived with her half-sister for 2 years.
They're loud, and definitely herding dogs. Both girls like to use their voices, a lot. Not any more or less than my other herders, but they are loud.
Both the girls were FANTASTIC with the cats. Neither had been raised with cats, both were introduced to two itty kittens as adult dogs - no issues at all.
I have no experience with either of our girls having DA/SSA. Before I got Eden, the breeder was speaking to me about her brother but the breeder thought the dog might be a little snarky with my other male so we decided I should get the female (Eden) instead. Both the girls are very strong tempered dogs, but they have had a TON of dogs moving through (board and trains, work dogs, foster dogs, puppies, adults etc etc) and they have NEVER EVER had a problem with any of them. They are also fantastic at all sporting events they have been to. The two of them get along PERFECTLY and they were not raised as puppies together or anything.
Eden's temperament is totally outside of standard (that's why I got her), she's outrageously social, friendly, silly, go up to anyone and meet them etc. Poppy is more correct. She's more aloof, and she doesn't beg strangers to pet her - BUT she's totally social and safe. We have never had a problem with either of them meeting new people, of all ages. In fact, at one IPO trial, we handed the girls off to a gaggle of little girls (aged 8-13) and they played with them the entire day. We could see them the whole time of course, and the girls were raised with GSDs so they were wonderful with the Corgis but I don't know too many dogs that would've not only felt comfortable with that, but greatly enjoyed it like the Cardis did.
They're both very bright. Easy to train. Biddable. The food drive is out of this world. The toy drive is not so accessible in terms of using it to train with. They both like toys, like to tug, like to chase and chew, but neither like it enough to actually work FOR a toy. Food though, food can get them to do almost anything.
I can't really take credit for their upbringing at all. And next Corgi I add I will definitely going back to the same breeder. He absolutely was honest with what we were getting and he did a phenomenal job raising both the girls. They travel well, are easy to handle and manage, and are just all around awesome dogs!
Some photos....
This is Eden's playlist...so you can see how "trainable" she is. She's got titles in multiple venues.
http://www.youtube.com/playlist?list=PL17CBA52422E56ADD