It is os-independent having a very thin architecture with which it can offer unparalleled security and reliability. Unlike most other hypervisors in the market, this don't need a general purpose operating system clearing the hazards of processor overhead, Antivirus and other OS processor consumption. Its this feature makes it prominent in the market of hypervisors.
Room for Improvement:
Well, not much drawbacks actually. It serves the purpose it is designed for but still a very few little things that i have notices that can be called its drawbacks can be
1. Fault tolerance limits features available to virtual machines.
2. Automatic fallback of VMs currently not supported. This can be crucial in some environments.