SpongeBob, Soccer Star is a reasonably cute little SpongeBob book, but it's definitely nothing special. It doesn't seem to be based off an episode--not one that I've found, at least--and while it's not as moralistic as some of the other books, it's also not as humorous as a SpongeBob story should be. My biggest gripe, perhaps, is that while SpongeBob and Patrick are in character, Squidward is a bit out of it. Yes, his characterization after the premise is set up makes sense; he is definitely the type to get obsessed with maintaining leadership and proving his worth, but as for the premise itself... I don't recall any point in the series at which showed even the slightest interested in sports. He's more the music and dance type.
Let's not even get into why the heck Mr. Krabs thinks a Krusty Krab soccer team is going to earn him more profit publicity? They're already the only edible fast food joint in the entire town.
So it's an alright book for SpongeBob fans. Unlike many of the tie-ins, it doesn't take an episode's plot, suck the humor out of it, and inject a moral; instead, it's an original story with a hint of a moral in the form of SpongeBob's generosity and a bit of typical SpongeBob humor toward the beginning. It's not a great story by a long shot, but I'm sure young SpongeBob fans will be at least briefly entertained.
2
 (Spongebob Squarepants (8x8)) - Nickelodeon)
