No scope model in this world is or will ever be 100% bug-free.
What's more, it's a very inexpensive scope - you can't expect the development department to sit down and fix every annoying bug, the budget isn't there for that.
With bugs, a distinction must be made between functionally relevant and just "annoying" bugs.
Rigol and other manufacturers will generally ensure that their cheap products are stable, anything else is more of a bonus.
I wouldn't want to get my hopes up with the FFT.
The bug with the faulty window coefficients has been around forever and the lack of features such as average and peak hold will probably not be rectified either, as even the largest scope, the Stationmax , only has rudimentary FFT features.
As of now the scope is stable and has some nice new features, if you want something else you have to buy a scope somewhere else.