Alex Netkachov has posted some of his own thoughts about Microsoft's recent SQL server 205 driver for PHP:

I can add that a few years ago I had bad experience with MS SQL PHP extension. It was just impossible to use it in production environment. These days MS understand that PHP is a very popular programming language and step forward to the community

He also includes a list of some of the things that the driver includes/makes possible such as the fact that it's not a PDO or OOP driver, that there's no source posted for it and that it does support data streams.