Works good for me, but I don't run games. I use it for test installations of previous OS X and Linux versions, and use several Windows applications under XP, 7.1 and 8.1.
The time I save by not rebooting to run other OSes native easily offsets the minor hit in performance my usage sees.
I don't think I've had a problem at all with version 10 except the handling of hidden docks on guest OS X vs. host OS X. VirtualBox does it perfectly, P10 works easier if one isn't hidden.
Do you have any experience running a distro using the most recent Linux kernel? I did some reading on the Parallels forums and it seems to break installs or you cannot successfully do a new install using it at all. Parallels tools has issues, etc.
I read one comment indicating a similar situation with VMware that dates to late last year and remains unresolved but it's just a second hand remark and I have not personally looked into that or visited the VMware site yet.
I am considering a move to VMware if it works as well for older games as Parallels does after my recent experience with them claiming it was impossible to start a virtual machine with Parallels 8 in Yosemite which is absolutely not true. I and others running Parallels 8 have no problem running VMs with Windows XP and Windows 7 at least (in my own use) and running games, etc. in them. Anyway, separate issue but it left a bad taste.
I want to evaluate the current state of Linux in a variety of distros I've used in the past and a VM is the perfect way. Reading the Parallels forums I won't even bother trying it with Parallels.
I might investigate VirtualBox and see if it is up to snuff for current Linux installs and use that if it is. I would not expect gaming support with that though unless they have come a long with accelerated GPU support and I doubt they have. Maybe I am wrong though. It was experimental last I knew.