I just finished this, and then went and read some reviews at Amazon.co.jp. If you're going to read the reviews, only read the bottom two (the oldest two). One of the newer ones has a major spoiler in it.
Let me start with positive side first. The heroine of the story, Haru, is really likeable. The supporting female character, Makoto, is also really likeable. To put it bluntly, they remind me of Iriya and Akiho, but not necessarily because they have similar personalities. It's more of an intuition thing. Haru is one of those characters one might fantasize about, but with an understanding that she's not real. It's a bit different from, "I wish I had a girlfriend like her," but rather, "I wish a girl like that existed." It's a subtle difference, but it's an important difference, to me anyway.
Story starts out a bit slow, but it works out really well because when things finally start to get revealed, it has a lot of impact. If things moved too fast from the beginning, the impact would have been compromised.
The main complaint I have is that the main male character, Masatoki, is a whimp. I mean, the kid has no volition of his own. Even Asaba wasn't this bad! Masatoki does improve at the end of this volume, but it came so suddenly, I didn't think it was realistic. Asaba at least went through a lot before becoming decisive about his path. I don't know, maybe Masatoki will eventually show he's a man, too, not that I care that much about male characters. Seriously, I had no qualms about Asaba being liked by both Iriya and Akiho. I don't believe I'll be so tolerant with Masatoki.
Putting aside the similarities to "Iriya no Sora, UFO no Natsu," which could have both positive and negative effect on the reader, I'm finding myself wanting to read more to learn about Haru and Makoto. Unfortunately, the second volume hasn't been released yet! But then, that's never a problem because I always have more books to read than I can go through.
One last thing. As one of the reviews at Amazon.co.jp states, if you're interested in this book, but have not read "Iriya no Sora, UFO no Natsu," you absolutely must start with that one. I gave my copy of "Iriya no Sora, UFO no Natsu" to Sanada Asami during Fanimecon 2006, because she said she liked "Saishuu Heiki Kanojo" a lot and she hadn't read "Iriya no Sora, UFO no Natsu." Of course, I bought my replacement copies already. After all, I love Iriya. See my favicon?
Front cover shows Haru. Yes they're the same person. Oh wait, that's not exactly true.