Danmaku Unlimited 2 is a brilliant little game, in ways that may not seem at first apparent to newbies, or non-bullet hell gamers. What it isn't is groundbreaking, or genre defining. What it is, however, is a master class training program into danmaku shoot 'em ups, and it does it so well i challenge anyone to deny they've improved their skills while playing.
You may have seen games such as Touhou Project, recent Cave titles, or general Japanese Doujin releases and thought "it looks amazing, but i would suck" - this game is for you! DU2 lets you get used to things, before making you work - something a lot of these styles of games lack. I've been playing "Danmaku" games for years and was pleasantly surprised at how configurable this title is, and how much it wants you to get better.
This game is one of the most configurable Shoot 'Em Up's on the market - it goes from easy peasy, to OMFGWTF just happened in a few clicks - catered to your needs, and all the while throwing bullet patterns at you that you will recognise in other such games. Training ;-)
Danmaku Unlimited 2 makes you a better shmupper by design, so if you are so inclined, you'd be stupid not to play it.
BTW, it has a great soundtrack too! Everytime it boots i want to kick ♥♥♥! It tells me to. And so i do.