Is it worth my time?

Well, KH Ultimania has some of it posted on their site, but they never update (and Vol.2 of KH:CoM isn't up), so you're better off just buying it.

And yeah, B&N has them. You just have to know where to look. :)

And so far all four volumes of KH are out. Then there's the two volume Chain of Memories saga. And finally the first volume of KH2 is out right now and the second volume's coming later in the year.

 

the mangas good.my favorite one was chain of memories book 2.

 

the KH1 manga was extremely short in my opinion, but I guess that's what happens if you don't count the gameplay in the actual game and stuff. For example, the battles are shortened to like 3 pages or something. I only have the german version and some jokes weren't as funny as I expected it would be o.O
And yes, it's a bit more childish and humorous but that has been done for the younger people.

The CoM Volumes were much more interesting somehow, dunno why xD

If you are a big fan of KH and Manga, you should buy it ^^

 

It's cool,and some parts are really funny. so yeah you should read it