This is another piece that I have had just forever, and I don't think it is going anywhere anytime soon. I got it around the same time as my Clairvoyant jacket, which was around 7 years ago. It has it's fair share of patches, and I don't think I will ever be able to get the stink fully out, but I take this thing everywhere. I pull this piece out whenever I am going to be on the move, but wanting insulation. Sure, I might get a little sweaty but this thing breathes like a dream, and keeps me warm quite well. Many companies have a version of this jacket (Atom AR, Rime Lite, Refuge/Ascendant) and there are pros and cons for each of these.
The Nano Air happens to be the one I bought all those years ago, and I have promised myself not to buy another one until it craps out on me, so here we are! In all reality, the jacket fits me well, there are pockets where I want them (two hand pockets and a chest pocket) and it keeps me warm. I have no particular downsides to this jacket besides the fact that it isn't quite as light or compact as my down jacket is. But I don't expect it to be. Maybe when this eventually falls apart, and I get a new synthetic insulated jacket I'll realize the faults of this one, but so far no complaints.
PROS:
Breathes really well
Keeps me quite warm
Fit is great
I like that this piece has no hood, but for some that may be a con.
CONS:
Durability is possibly a con, but I've had it for 7 years, so I expect some wear and tear