Underrated shoot'em'ups

Today I was taking a look at my Dreamcast games and came across Zero Gunner 2 again.
For anyone unaware of this game, it's pretty much your basic shmup using helicopters by Psikyo, but with a nifty gimmick: you can change the direction you're facing, much like the PC "Warning Forever".
The first Zero Gunner is apparently emulated in MAME, but I've never played it.
I never really heard much talk about either of them, didn't even heard of the series until 2 came out. It's rather nice and only moderately difficult on normal (with 8 difficulty settings I beleive).

Anyone else familiar with this game or the series?

If anyone else has some shmups they feel are underrated and not talked about enough, feel free to post about them!

Dunno if this is underrated as such but I never hear much talk about it even though it is quite possibly one of the best and most original shmup around especially on the GameCubes 'limited' range of games.

I love the system of white and dark and the way it is cleverly implemented into the game. Might sound easy but it is one of the hardest games I've ever played - meaning it is one of the best of course ;)

PS: do tripcodes work on world4ch or just image boards?