I just recently got a suit from them, 2-piece, single-breasted, grey wool-flannel fabric with pretty subtle overcheck (as seen in the pics), slightly roped shoulders. The suit is actually still at my tailor's but some short notes.
In terms of fit they are on the "slim / fitted" side. I'm usually 46 in most of my jackets (Lardini, L.B.M 1911, Pal Zileri) and this one is 48(Regular). According to themselves the sleeve lenght is also on the short side (Italian length).
There's decent amount of handwork (I'm not an expert on these and didn't check it out that properly yet, but at least all the button-holes are made by hand for example) and the finishing seems to be done with care. The construction is pretty lightweight with 1/4 lining.
Some nice details (or I think some like them and some don't) such as the "one-button sleeves" with blue-toned buttons.
I have no personal experience of Kiton or Attolini but based on what I know and what I've seen I wouldn't really compare G.Abo to them. On the other hand, the price-quality-ratio on G.Abo seems to be more than good as the suits start from 800 euros and sport coats from 500-600 euros (IIRC).
I will visit these guys at their showroom during Pitti Uomo next week so after that I will probably have more to tell and some more pictures as well (+ experience of wearing the suit of mine).