The largest complaint I have with regard to both freeware and payware aircraft has largely to do with roll rate. In real life when you roll an aircraft, it obviously begins to roll. But as soon as those ailerons are back to neutral, the rolling motion STOPS. IT doesn't keep going for another 5-10 degrees... it stops as soon as that stick (or yoke) is neutral. Perhaps in a 35,000 lb jet roll inertia can be more visible, but certainly not in anything like an Extra 300 or Decathlon. All you have to do is go to Youtube and do a few quick searches and find some external vies to see how precise the aileron movements are and how instantly they cause the aircraft to move or stop moving. There is no to very little counter aileron to stop a quick roll rate.
Now having said that, this may be one of those weird quirks that MSFS has built in, such as it's lack of the ability to naturally spin an aircraft. Also, I really don't have any complaints with the freeware and payware aircraft I have. They are wonderful works of art and I was just pointing this out as another way to make things more realistic. However, the topic I mention I have never seen fixed in any models.