is it worth to buy shooting love 10th anniversary? I'm still debating.....
Triangle Service games are a score-oriented taste. I've never been wowed by one of their games, graphically speaking. So I guess it depends if you want to "just shoot stuff and watch pretty explosions", or if you like experimenting with different scoring techniques.
I stopped by home over lunch to compare XIIStag to XIIZeal, and it looks like the scoring mechanics carried over well. There's a variety of attacks for hitting enemies beside or behind you, and secrets everywhere when you used those to attack enemies in unusual ways (not just hanging out at the bottom of the screen using normal shot). There's also some hidden weak points that larger enemies expose if you are patient. You'll know you're kicking ass when it does the twelve-rap, "TWEL-TWELV-TW-T-TWEL-TW-TWELVE!"

. So yea, lots of experimenting if you're into that. On the down side, the first level still feels like a tutorial, with enemies that literally do nothing but line up in rows to show you how to score correctly.
DeltaZeal is a bit of a mystery to me since I didn't play any G-Stream. It looks like the branching paths are based on defeating certain enemies quickly. So there's a balance between increasing medal value and going for quick-kills to get higher scoring paths. This will be a difficult adjustment for me since I am used to grabbing every medal possible in Raizing games.
In any case, I can't imagine this disc will sell many copies, especially releasing the same day as Saidaioujou.