The driver is everything that runs on the CPU that runs your kernel and applications - so yes, they have open-sourced the video driver. That's the most plain reading of the term "video driver".
On top of that it's perfectly legitimate to say "the interface exposed by the closed-source firmware is very high level, so this release doesn't let improvements to the OpenGL/ES implementation be made.". But calling it a "lie" is twisting words beyond their breaking point.
Obviously it would be nice to have the firmware source and toolchain as well, but it doesn't look (to me) like they've implemented the GL functionality off-CPU as end-run around open-sourcing the code that runs on the CPU, but rather for engineering reasons (offloading work from the underpowered CPU).