So far I only heard good things about the new Aero. It is a Naish, so we wouldn't expect anything else. It is supposed to have good handling and is very good to relaunch. So for beginners it is a very good altenative to 2-line kites and due to its handling an alternativ for proriders who don't need too big airs.
So guys, if you have the change to test it, you should.
And if anyone knows something negative about it, please let us know.

I've heard that it is said to be good only in smaller sizes. Seems that the 16m and 20m are not as good as the others.

do you know exactly what is better and what not?

No, as I said that it is only something I've heard, but it is not the first time I've read about it.
Actually most of the people who have tried the Aero so far were flying 12m or 9m, in those sizes the kite is said to be outstanding.
But, for the larger sizes Aeros could be too slow turning.
Waiting forward reveibing the test results from Axel'air.

I have seen both the 12 and 20 in action. The 20 was being used by an old guy in Florida when I went. He was kinda heavy, and was using a twintip probably 160 cm big. In 10-11 knots, he was going upwind no problem with the kite locked off, and jumping about a meter anda a half, the thing was really stable.
The 12 I saw in Progreso, Mexico. A friend of mine has it, he took it out like in 25-30 knots, with a naish mutant, he weighs like 65 kilos. Obviously, he could not stay upwind, and was really overpowered. Who said mexicans don't have balls!
Andres

Have a look on what they say about Aero at:
http://www.windysite.com/windysite.html

hy everybody
note: i have the aero 10 end 16
for the most wind up from 3 to 6 Bf. is very good drivin. a verygood handling and good relaunch. (16 more hevy vor return)
we was over the Easter in hyeres end by 8kn we saw an aero 20 in action!! Jumps over 2 meter with an 170 board (Respect)
much fun on the Water!!!
Andy