Pro Available for Windows and OS X
The font is available on machines running Windows Vista, Windows 7, Windows 8, and Windows 8.1, as well as part of Microsoft Office 2007 and Microsoft Visual Studio 2010. Otherwise it can be downloaded from Microsoft's homepage. It can also be set up on OS X machines with instructions on how to do it available here.
Con Font size can't be changed gradually
Letter height is the same for 9 and 10, and for 11 and 12 pt. When switching from 10 to 11 pt, letter height changes abruptly (whereas line height changes gradually). This makes it impossible to choose exact letter height on a standard display. Size can't be set to 10.5 pt, for example.
Con Highly aliased with ClearType
Consolas is specifically designed to work with ClearType antialiasing, so it becomes highly aliased when ClearType is not turned on. This can be alleviated to a degree with any basic grayscale anti-aliasing.
As an OpenType relative of Consolas, Inconsolata works well without ClearType (Inconsolata-g being the most popular variant).