Anyone tried this one yet ?
Demo is here. Full game is also available from their site and also from Gamers Gate.
Looks interesting.

I only played for a few minutes and I have to say that I had fun.

I bought it ('cause I love every god damn Nifflas game), and loved it. It's quite short though, so I advise you to buy a second serial for 2 extra bucks on Nifflas' website and give it to a friend!
Dunno if the +$2 offer still holds though, but it's worth it.

"For 12$ you can unlock the full version including 4 extra planetary systems."
This offer ?
Edit: I guess that's just the regular price. I don't see the offer you mentioned so i guess it's no longer on offer :|
Edit2: Yep, just took a look under news and found this :(
"I had forgot to end the Saira extra license for $1.5 offer, so it was still available a week more than intended. Now it have ended though."

I had fun initially, but the later levels proved to be far too frustrating. The jumping puzzles require too much precision to reach, that it becomes more annoying than fun to try to get past them - I am of course referring to the lava level. Part of the challenge was also added by the (lack of) responsiveness of performing certain moves, like jumping from a wall sliding position. I was prepared to buy it, but after getting far too frustrated of having to restart the same checkpoint for that lava stage for the 8th time, it kinda killed all interest I had.
It seemed to be a case of "let's make this game exponentially difficult as it progresses", rather than "let's make this game more challenging, yet fun, as it progresses".

I started the demo a few days ago. I like it. It's pretty and plays well. The puzzles seem alright, but in a way, I prefer the minimalism of Knytt that was as stripped down as a platformer could be. Nevertheless, Saira seems like a good game and I'll likely buy it because Nifflas deserves the support after releasing the wonderful Knytt and Knytt Stories for free.