- It seems faster than VMware Fusion
- It's free and mostly open source
- It's just a bit rougher around the edges
The VirtualBox Open Source Edition (OSE) is the one that has been released under the GPL and comes with complete source code. It is functionally equivalent to the full VirtualBox package, except for a few features that primarily target enterprise customers. This gives us a chance to generate revenue to fund further development of VirtualBox.What this means in practice is that it's not easy to use the open source version since there are no precompiled binaries and no installer. Hence, you're stuck with the free, but not open source version. The two things that I actually care about that are missing from the open source version are USB support and a gigabit ethernet controller. Oh well. That's still better than what I had to pay for VMware Fusion.
Please note that the Open Source Edition does not include an installer or setup utilities, as it is mainly aimed at developers and Linux distributors
As for speed, I haven't actually timed it, but the BIOS stage of booting is crazy fast, and installing Ubuntu didn't seem to take forever like it did under VMware Fusion. Of course, this could be a figment of my imagination. I can't remember if I had the same amount of RAM when I installed Ubuntu under VMware Fusion either, so take my comments with a grain of salt. I will say that sound seems smoother.
Speaking of sound, by default it's turned off. That was easy to fix.
By default it uses NAT, and the host computer cannot connect to the guest computer. Since I like to login over ssh, that was a no go. I figured out how to switch to "Host Interface Networking", and I was happy again. In general, this is one area where VMware Fusion seemed to just work.
Just like VMware Fusion, VirtualBox has custom kernel mods for Linux. Installing them was easy. Once I did, the mouse was perfectly integrated between the host and guest computers. Furthermore, full screen mode now uses the same resolution as my Mac. Sweet!
To be fair, VMware Fusion does the same thing. Of course, this only works for Linux and Windows. There are no kernel mods available (that I know of) for other operating systems like FreeBSD.
One more feature that I haven't bothered trying out is:
Shared folders. Like many other virtualization solutions, for easy data exchange between hosts and guests, VirtualBox allows for declaring certain host directories as "shared folders", which can then be accessed from within virtual machines.Anyway, it's good stuff. I'm guessing that VMware Fusion is probably better if you need to run a Windows client (because of all the "Fusion" functionality), but if you just need to run a Linux client, VirtualBox is free and good.