Well it seems a lot faster, especially when doing a cloth sims using Ncloth, and animating a smoothed poly character with ncloth attached, which I think is down to the multi threading/core enabeling of maya as in simulations using 8.5 only used one core, other than that Ive not really played around with it that much (as ive got to do my uni work on it more than having a play)

I really like the viewport cube to quickly get form one ortho to another using the persp view, thats probably going to save me a few spacebar and mouse clicks when modeling and selecting.

as you've seen its faster, although I dont really see much difference in the boot up, to fully launched as it only takes about 30 seconds to fully load on my PC and I wasnt really looking for it.

As for the render times did you have use all processors enabled on 8.5 as it used both of mine to 100%, although ive not really compared the two.