I wasn't sure how I felt about the first SS4 transformation because of Goku needing to become the ape first. I know in DBZ, Vegeta was able to control his ape form fairly well but Goku couldn't after all that time? Seemed weird to me. I mean I guess Vegeta could have practiced controlling himself in that form but still. Either way, when it did happen and they showed Goku's new form, I ended up loving it. I do like the fusion here as well but I still think the initial first SS4 transformation was better.
I don't like much from GT, but this was a pretty cool moment. Omega Shenron had been kicking their tails all over the place and the fusion between two SSJ 4's really demonstrates how powerful the technique is and how much more powerful they had become.