Rode it four times earlier this month. My DW and I had ridden it many times pre-refurb, and both think it is much better now.
1. It is now much darker inside SM, so you can rarely see the tracks, and when you do see them it is very vague. This is a HUGE improvement, IMO.
2. The starfield effects inside SM seem much brighter and more numerous, and we liked that.
3. The soundtrack is different. My DW and I liked it, but I cannot remember the old one.
4. The "launch" where they take you uphill is very different and much improved.
5. The ending/slow down is different and improved, IMO.
6. Everyone says the ride is "smoother" now, but I could not tell the difference.
7. I think the wheelchair loading is different. I cannot remember what they did before (if anything), but now they actually pull a ship off the track to load people in wheelchairs, which allows them to continue launching ships without delay. When the wheelchair person is loaded in the ship, they put the ship back on the track and launch them.
8. The queue is completely different, although the loading area looks very similar to before.