I picked up Carnival Games for the Wii today at Gamestop. They were nice enough to get it out of the back (I had it on reserve) and add it to the system (again, kudos to this branch's customer service!) for me to check it out.
Now onto impressions...
The graphics do run in 480p and 16x9. They are fairly simplistic, but have their own charming style. Mii integration would have been nice, but the character creation (at the front) allows one to create a somewhat reasonable facsimile of themselves. There are quite a wide array of mini-games. In general, there are no broken mini-games ala Super Monkey Ball: Banana Blitz. The cursor is stable, and although--of course--no games are 1:1, they control fluidly and respond pretty much instantly to the user's actions. Load times are pretty much nonexistant and I'm impressed at how quickly you can launch back into another try if you want to play again.
Alley Ball is one of my favorites thus far. It's pretty simple--aim (left and right and spin) then flick the remote up. Being the Wii Sports Bowling alum that I am, I wanted to rear back and then let it go.

If you miss, a funny guy will start taunting you: "I think you're a cool cat, but maybe this just ain't your game!"
Dunk the Punk is another great. Gotta love the cheerful Carnival guy inviting one to "dunk our punk." Each time you hit it (a timed throw-like motion), it gets smaller. The punk will also taunt you, naturally, being the punk he is.
There are also several shooting games (Shooting Gallery where you shoot classic arcade ducks is a favorite) as well as others such as Hoops (toss a basketball, the one mini-game I can say has a bit odd controls, but can be able to get used to), Ring Toss (challenge, but fun) and so on.
Each time you score, you unlock things to customize your character or collectible prizes. There are also mini-games which can be redeemed with tickets (main games like Alley Ball do not need tickets) like The Claw and one where you are under a Plinko-like field, moving a squirrel catching nuts as they fall.
The music is there simply for background, and is neither intolerable nor remarkable.
I haven't had a chance to try multiplayer yet.
Overall, a good mini-game collection. There's little "depth" here (no deep plot), but there is replay value from fun games, unlockable "super" games, prizes, etc. I feel it's worth the $39 USD if you liked Wii Sports, Wii Play, etc. Sure, if you are one of those "Wii has NOTHR Mini-GAmezzz. It esss dooooomeed!!" people, it won't be for you, but for some enjoyable lighthearted fun with unique Wii controls, I'd say it's worth a shot!
If you have any specific questions, I'll try to answer them when I have the time.