I downloaded mine from the Ikarus website (via the upgrade process). It was most likely the largest download I have ever made, somewhere in the neighborhood of 7 GB when all the files were downloaded. You would definitely want to have some strong broadband or lots of time to do it. I think it took a little over 1/2 hour on my cable connection.
Running very nicely on my newly built system with a single (for now) GTX 780. Frame rates seem to be stuck on 125, even with max details :-D