Graphics look nice, and I'll admit, I've not seen later levels of the game. What I have seen however, doesn't impress. Bullets that shoot straight up, fading away near the top of screen, where all you need to do is stick to the bottom of the screen? Looks like bad design when viewed through my eyes.
Then the score system, a combo has a 3 sec limit. So does that mean there will be up to 3 second lulls in anything being on screen?
3 seconds in a huge amount of time in these kind of games, Dodonpachi for example is about half a second, before the combo breaks.
If the enemies were set up in a more Ikaruga based way, then maybe a 3 sec limit could work -- but I don't see anything that indicates the level design will be that intricate.
It did remind me of Defender, which was a great game in its day. The developer of ResoGun, is saying this is a shooter for the new era though. I see no evidence of that, other than pretty graphics.