Awesome idea. I'll also take this chance to pirate away if I don't have the game. I also find myself being a bit harsher than most PCE fans on most game reviews, but I figure that'd just make things a bit more interesting.
Anyway, so I tried out the Daisenpu Custom for a few hours, and overall, was very underwhelmed. It's a CD-ROM2 game, so I don't know if the card version is better (I get the feeling it may be -- I was really seeing how more RAM could've helped this title), but carrying on...
First of all, I found the choice of colors to be pretty drab/off. For example, quite a bit of lanscape was in this turquoise color, and I don't recall seeing many turquoise landscape in real life. Not to mention, there aren't a lot of detail in the landscape -- some are completely flat, so there are times when you're flying over a single-solid color landscape like in the pic below. It almost looks like you're flying over calm water at best (with tanks on top!), or at worst, just lazy development -- I vote for the latter. Sorry for the crap cell phone pic, but my point should be evident in the pic.
The animation wasn't much better, as explosions are a quick firecracker-like pop, and that's it -- no crater left in the hole like the MD (and presumably, the arcade) version. When you release a bomb, you just see like a solid explosion for a few seconds, not much else (no bomb dropping down or anything like that).
The music was decent -- a nice tune that keeps an atmosphere of suspense -- the bright point of this title in my opinion.
As for the gameplay, I found this one to be a bit tricky. There's definitely something challenging about shooting away at ground based foes who don't have far movement range, but because of that, you tend to close in on them to get rid of them, but then they might shoot off a pea round just at you're about an inch away from them. And even some of the minor peons take a good 5-6 shots, so that makes things even more difficult. The power-ups definitely help, but not enough to overcome the handicap you have against the multi-hit taking foes, and it really takes some skill and/or rote memorization to get your way through far in the game. I didn't notice the squadron of help you got in youtube clips in the HuCard and MD versions -- that definitely would've helped in certain areas.
Overall, this title doesn't get mentioned often when it comes to good shooters for the PCE, and for a good reason. I'd say it's definitely in the lower-leagues compared to the many alternatives for the system.