I'd originally read this when it first came out, but I recently re-discovered and re-read this volume.
First off, this series has fanservice. Panties, boobs, and other fanservice-ish bits are thrown into artwork, but surprisingly enough... it works. It's there and its intention is very obviously to titillate, but it's not done in a manner to where it's the absolute main focus or to where it's so intrusive that you'd roll your eyes at the various ways the mangaka has forced the female characters' underwear to be shown. (OK, some of us might do that even with minor fanservice...) What impressed me is that the fanservice does NOT come at the sacrifice of the plot or character development. You might get flashed by a character's panties as she's leaning over someone, but our female characters are not just there to be boobs and butt dispensers. Yamada tries to actually work the fanservice into the story for the most part and doesn't have Rion's clothes constantly flying off her body. I'm going out of my way to mention this because I'm pretty impressed by this. The series might be taken a little more seriously without the fanservice, but for the most part it doesn't get in the way.
I rather liked the idea of a bunch of teens landing on a mysterious island where ancient creatures abounded. I'm glad to see that it's not dinosaurs, but other creatures (mostly furry ones) that aren't usually the ones you'd imagine when you think "extinct animals from way long ago". It lends a little freshness to the idea of kids against nature, which is something that's very much needed since for many this will greatly resemble LOST or any number of "weird island, ancient creatures" types of books. The characters are fun for the most part and while they're a little overly typical, they're also likable for the most part. I would like to see our female characters become more assertive, though. Other than cooking or knowing limited medical skills in volume 2, so far they're mostly just "there".
This is just a fun volume and despite some misgivings, I can't help but like it. It's something that I can easily see catching on here in the English language manga market, especially with action fans. People looking for something more plot intense will be slightly disappointed since the story so far is more "run and fight and run", but overall this is just one of those series that you like just for being itself. I have to say that the more I read of it, the more I can't help but like it- warts and all.