Meh...can't we at least get a 'mixed' opinion instead of a thumbs up or down on this one? :-\
I thumbed it down, but it is really not without merit. The thing is: you can easily see the good points of this game. Visuals are decent and it has a good atmospheric music to go with it. And even the controls are okay...perhaps even decent.
What it doesn't tell you is that it's hard. Extremely hard. To the point of insanity, even. Sure, quite some portion of that is me being not good at lunar landing kind of games. As such, this isn't the first of this sort of game I've just quit because I can't avoid one insta-death astroid without setting a deadly course to the second.
The thing is: where games like solar 2 and osmos accept this difficulty of steering and don't get overboard with other things, solar flux adds more layers of frustratingly hard stuff. Stay too close to a sun and your shield melts away. Most levels have flares to pick up while traversing through insta-death asteroids, which means you have to do a pretty much perfect run. Some suns tend to explode, so there's that that may send you off into an object or deep space. Others have timers or require you to set a path you can barely see from your starting position.
Oh, and you have limited ammo, so better use it wisely (which is in most levels 'close to none', as you have to time your flare-to-sun injections perfectly so the resulting explosion sends you of to where you actually want to go).
Now don't get me wrong: I like hard games, and to a degree, it certainly is challenging. But I feel quite some of the difficulty should've been reserved for a hard mode (like the limited fuel and shields). Or that there'd be an easy mode without those things. And if recent hard games have learned us anything, it's that the levels should be short (which is, admittedly, more or less the case here) and shouldn't hinder the player. That's certainly an issue. After a crash, it insists on a showing a 'you crashed' message where you have to click to restart, and even then it insists on repeating the objective every freakin' time.
So in the end, I'm thumbing it down because this really shouldn't be your first space sim. The difficulty curve is, IMHO, just too high. It should be okay (and perhaps even great) to those who fully mastered the movement of games like osmos and are looking for something harder. For anyone else, I'm sorry, but I'd always advise those games first. :-(