Differences between Dragon Bird and most other games of the genre
Most importantly, Dragon Bird has a different approach to weapon / ship / shield
upgrades than other, pickup-based games like SkyForce Reloaded. (Games like
Xenon 2 use a hybrid approach: you can both purchase upgrades and pick up some while advancing.) You get no upgrades for free as a pick-up; this means you need to earn money by
1. shooting down as many opponents as possible
2. not exiting the game and not being killed easily (then you get a penalty and lose half of the main boss' credit)
This also means you'll need to play through some levels at least several times to be able to purchase a weapon (or another
upgrade) to be able to pass the next. For example, I've found it's impossible to get past the second stage without purhcasing the $25000 triple cannon. In order to be able to purchase this weapon, I had to play through the first level at least three times. The repetitive need to play through the same level can become pretty boring and annoying when compared to, say, SkyForce Reloaded's linear approach not forcing you to do the same.
Enjoyment factor
The game itself, while is technically far inferior to SkyForce Reloaded (far less spectacular or plain non-existing visuals like explosions, much more spectacular 3D effects etc., duller music), has turned out to be pretty entertaining.