Here is a size comparison photo for everyone to enjoy
That's a Space Marine Commander down there near its foot, next to a forgeworld Ironclad dreadnought next to a Bastion. That should give you a pretty good comparison on sizes compared to 40k scale.
I can't say enough about this model...It was a joy to build and is an excellent example of a well engineered model. There is so much articulation built into it that it didn't need any conversion work to get this pose.
I left the arms poseable because you can and its fun to point the guns at things.