While I agree with Peter's review for the most part, I wouldn't say that the barrel of monkeys was completely full. I had to knock a few points off, partially because I don't think monkeys are intrinsically entertaining, and mainly because I found the game's technical shortfalls were serious enough to detract from my overall enjoyment.
Looking at the main game, I found it to be incredibly too difficult for anyone except experienced players past the Beginner level. You'll want to skip this mode entirely and go straight to the mini-games for party night. Personally, I thought the difficulty of the Advanced course was just right, but the Expert course was smash-your-controller-and-make-an-evil-grimace-while-choking-the-person-next-to-you type of insane. I realize they're called "Expert" for a reason, but this is ridiculous. What really grates on me the most is that it feels like the games controls are fighting you right when you need them the most. Fortunately, there are unlimited continues available after accumulating 20,000 Monkey Points, but since they sadly only accrue in the single-player main game, it'll be a while before you get them.
About the controls, I'm going to have to disagree with Peter's feeling and say that I did not find them to be pleasingly responsive or spot-on. The Monkey Ball itself feels like its constantly rolling on ice, doubly so on inclines or moving objects. Its not a big deal on the easier stages when you're barreling through benign layouts at high speeds, but the game becomes three times harder than it needs to be when you're attempting delicate maneuvers. (Which is all the time, on Expert.) Couple that with the cameras wild and disorienting swinging motion every time you try to change direction, and you've got the perfect recipe for a disc snapped in half. While Sega games are generally known for having flawless control, they have never been known for having good camera setups. (See virtually any Sega game in the 32-bit era.) Super Monkey Ball strikes out on both counts.
Enough about the single-player, lets talk multi. Super Monkey Ball actually delivers a pretty good assortment of things to do if you have extra controllers and a few friends. My personal favorite was the Billiards game, which is simple, but excellent. Monkey Target is also lots of fun, and very reminiscent of the original Pilotwings. Monkey Fight was good for some laughs and decent in a button-mashing kind of way, but its too simple to keep you occupied for long. The other games weren't as well done as these, in my opinion. Monkey Race was instantly forgettable, and the Bowling was atrocious with its spastic directional indicator. Mini-golf is something that I love in real life, but I loathed it here since the courses don't have curbs to prevent your ball from rolling off the sides and dropping eight miles down. It may sound like whining, but when you've got four people taking multiple ten-stroke penalties for being unable to make any of the "three par" shots, you'd think they would have eased up on the extremeness of it. Boredom and frustration aren't two things you want when you're trying to have some low-impact party fun.
In total, the game is not completely without its charms, but be prepared to deal with the wacko camera, touchy controls and serious difficulty of the main game. At $50, the value of Super Monkey Ball is pretty questionable if you plan gaming solo. However, there's some decent fun to be had here as long as you have plan to get your groove on with a some buddies during a weekend get-together. Drinks with umbrellas might help. It wont be remembered as a classic, but with the sparse offerings in the GameCube's library so far, you could do worse.