For purely technical side:
Otherwise ok, 3 things very annoying:
1. Right frequent updates
2. afterwards always reinstall Parallels Tools in the guest systems necessary
and apparently always during this Parallels update times is the Parallels Server
overloaded, so that that lasts forever .....
3. If you have eg Windows guest systems and the extremely frequent Windows updates
einspielt, it happens that then screen resolution / font does not fit anymore.
Remedy by reinstall Parallels Tools ... suuupernervig.
Never again .... mainly because with VMWare a professional and with
the free VirtualBox two alternatives are available.