I like Half-Life 2, but I certainly don't love it. To be honest, my biggest impressions of it are that Lamarr is adorable and Gordon Freeman looks really good in glasses. That's it. I really
wanted to love it, and I
tried to, but...there isn't even a word for it. Not dull, or boring, or bland, just something missing. That being said, I still follow news about the franchise whenever it crops up as though it were one of my favourite games, and I'm one of the people waiting for the mythical Episode 3. I think I'm a lot more interested in reading about the game than what I am actually playing it.
The first one was a lot more fun than the sequel, too, I thought.
For the second question: A cat. A sidekick dog -- especially if it were one that talked, good God -- would be one of the most annoying things I'd ever encounter, ever. ...I hate Scooby-Doo.
EDIT:
TheRightToArmBears said:
I don't really like it. It feels cold and clinical, like all Valve games.
I think that was the word I was searching for, actually. Clinical. In fact, that's perfect. It was all very emotionless and detached. Something like that works for Portal, but not Half-Life.