I find their models to be weak, almost cartoonish, without detail, and their panels are weak. My opinion on them is don't pay for stuff you can get for free with better quality to boot.
Case in point: Blackhawk. Abacus' Blackhawk sported a terrible cockpit (a Blackhawk's glareshield is canted at the ends. Not modelled), an even worse flight model, and for some strange reason decided to slap that silly Army of One logo on the side of it.
Over at Hovercontrol.com on the other hand they've got a BH with the best .air file I've found yet, and like 20 skins. And it won't cost you a penny.
Abacus' Flight Deck III....the Tomcat can't seem to stay in the airwith the wings swept back unless you're in burner (hmmmm) according to PCPilot. The CH-46 flight model is horrendous and has a panel with only a few guages on it. Save your movey, folks, and hit up the web. You'll find dozens of sites like simviation.com and hovercontrol.com