Many things conjoin and conspire to make the Squirrel squirrelly right near the ground. If it were "simply" the low tail rotor, 206's on low skids and certainly 222's would be similarly afflicted. Unless there's one on the left side also, the strake on the right side of the tailboom would seem to be Eurocopter's attempt to take advantage of the Coanda effect to lessen the right-pedal demands at a hover.
Rotorboy correctly brings up the fuel sloshing in the unbaffled plastic tank (although at 146 gallons it must have come out of one really long-range Peugeot). This can be uncomfortable, not to mention the source of PIO, and one that is certainly not needed when other factors are coming into play.
People have mentioned the rounded belly and how it affects the hover airflow. I suppose that's as good an excuse for my squirrelly hovering as any. And it probably does play a part.
I've never figured out Eurocopter's philosophy on control harmony. The D-models I flew had notchy collectives even with the friction all the way off, the pedals were strangely stiff considering they were boosted, and the cyclic was your typical "wet noodle." The cyclic, collective and pedals all ought to move with the same perceivable effort and effect, and this did not seem to be the case with the Astar. Ease in some pedal and nothing happens at first. A little more and...whoa, that's too much! Eh- maybe it was that limber, elastomeric tail rotor.
Adding to this was the puzzling cyclic linkage. The French do like a "sporty" feel to their helos, but the gearing of the Astar cyclic linkage and bellcranks seemed to me to be needlessly "quick" considering how responsive the rotor system is. Perhaps in designing the AS-350, the Aerospatiale engineers used the same basic control linkage ratios that they used with the (non-starflex) Gazelle and wet-head Dauphin, which were both sporty without being twitchy.
Although some pilots seem to adapt to the Astar flying qualities quickly, it takes awhile for many others to develop a feel for the aircraft. Fly an Astar at night, when the landing light illuminates the very front arc of the rotor disk. Even the tiniest movement of the cyclic causes that arc to jiggle up and down. To my mind, that's a control system that's not got the right bellcrank gearing.
High-skid or low, the Astars I flew all seemed to get weird right near the ground. It's aggravating because placing a skid exactly where I want it is neither as easy nor predictably accurate as it is in a Bell (or virtually any other helicopter for that matter). Flying shouldn't be that much work.