Even though yes it is indeed an old woman they use for the Emperor in the original theatrical ESB, it looks much better lighting wise.
I liked the idea of them incorporating McDiarmid, but when I saw it, I cringed. It looked slapped on, and MY GOD THE DIALOGUE. They killed the atmosphere and overall power of the original scene, and tried to explain some excusable plot hole. Lucas could have done it right, had they simply used the same lighting and dialogue, but no. As usual, he mucked up more than he helped.