Performance is always a matter when it comes to complex addons (The Flight1 ATR has to be in that category)
If you want all the eye candy and texture quality available, this bird is pretty demanding, but Flight1 has made a genious invention here called "ATR Configuration manager". Here you can select refreshrate on the EADI/EHSI, texture quality, virtual cabin or no and other gauge refresh rates such as the VSI. This makes it possible to tailor your own preferences

The learning curve is right between the shallow and steep. The systems are pretty straight forward, and if you are used to turboprops you won't have any problems at all.
There are many buttons to push and press, which always is a plus ;D
The Honeywell HT1000 "FMC" (it's basically a GPS system with an MCDU interface) is not as complex as its siblings in the large jets, but if you are new to these things you may need to read the manuals, but logical thinking will get you very far 8)
She flies very good, you really feel that this aircraft aint a Boeing 747 as she is quite sensitive to yoke inputs and turbulence, not a bad thing though :)
The sounds are very good, as you would expect in a commercial add-on