The trials are reminiscent of the silver scroll challenges from Black & White--the minigames found throughout the original game's lands. The trials here are generally more complex, and since they're hosted by giant animals like yours, if nothing else, they're more interesting to look at.

There are several new creatures, including a rhino.
Trials may be the brunt of Creature Isle's content, but they're not all of it. Early on, you'll have the opportunity to rescue an egg and help it hatch--and it hatches into a giant chick called Tyke. Tyke is actually quite small compared with your creature, though he stands many times taller than a human. He's just a baby much like your creature was at the beginning of Black & White. But while you trained your Black & White creature through direct interaction, you can't interact directly with Tyke--he's your creature's responsibility. Yet through your indirect guidance, you'll watch as Tyke learns all of your creature's skills--he'll learn many of them faster than your creature did.
Rearing Tyke is a fascinating process, and it'll give you back much of the same sense of wonder you probably felt when you first met your creature in Black & White. You'll see Tyke frequently gazing up at your creature, looking for approval with what really looks like the same inquisitive glance a child might give its father. Caring for your creature could be quite a burden in Black & White, but fortunately, looking after Tyke is a relatively painless process in Creature Isle since your creature will do a lot of the work for you. And soon enough, Tyke will be doing a lot of the work for your creature, helping tend to villagers or at least just tagging along. Of note, both your creature and Tyke will eventually learn how to assist with constructing buildings, which only humans could do (and very slowly) in Black & White.
Giant chickens weren't present in Black & White (a glaring omission!), and they're one of several new types of creatures you'll find in the expansion. You'll also meet a rhino, a gator, everyone from the original game, and more. As you complete each creature's trial, that creature becomes available at a central location on the isle, where you can either challenge it to a duel or switch your creature's body type to that creature's body type. It's a nice, new feature for being able to conveniently change to the creature of your choice or engage in Black & White's funny-looking one-on-one creature bouts. Some of the combat isn't optional in Creature Isle, which means you'll have to train your creature to be a good fighter if you haven't already done so. Making your creature heft the weight of a boulder around for a while should suitably prepare him for any brawling.
Many of the trials can be reattempted once you've finished them. You might not feel compelled to, though. There's no variation to the objective-based trials, and the competitive trials are paced too slowly to be of much fun after more than a couple of tries. That is to say, there isn't much replay value in Creature Isle, and you can finish all the trials in less than 15 hours. The game's skirmish mode does give you the option to play with your creature's apprentice, an option that both helps reduce some of the micromanagement and also generally helps speed up Black & White's competitive matches. Having two creatures assisting you instead of just one noticeably changes the dynamic of Black & White's core gameplay.

Creature Isle offers more of Black & White's most interesting bits.
Black & White came out nearly a year ago, and aside from the new creature types, Creature Isle looks identical to the original game--which means it still looks great. Despite the low-resolution textures and some polygonal warping in the game, the colorful, attractive environments and lifelike creatures are still a real pleasure to see. Like the graphics, Creature Isle's minimal soundtrack is mostly identical to that of Black & White, though you'll hear a few new tracks during cinematic cutscenes. All the speech in Creature Isle is new, though, including the voices for all the many creatures and other characters you'll meet. Despite the variety, not all the exaggerated accents you'll hear actually sound very good.
Creature Isle will certainly appeal to anyone who enjoyed Black & White in the first place. Surprisingly, though, it's also suitable for some of those who didn't. That is, if you enjoyed Black & White's gigantic creatures and its basic premise but didn't care much for the strategic elements that dominated much of the game, then you'll still more than likely enjoy Creature Isle. The minigames that comprise most of this expansion are like simple parlor games and aren't nearly as lofty as the concepts in the original Black & White. Still, between all the minigames and the inspired addition of a younger creature for your own creature to look after, you'll find that Creature Isle is a great place to visit.