So, I had a bit with it. So far I'm enjoying it (and my wife says she's having a blast). The UI is nice when you get used to it, finding a few small things here and there (like if you click on the top right corner of the sims icon when at work, you get to select what they're doing at work like in Sims 3). I like the art style, and I'm starting to understand some of the other changes too.
1. The Item customization. Ok, yes, I'd like to see more colour options here, but I do understand why they moved away from the pallet system they had before. There was no incentive to buy expensive walls for example, because you could just buy the cheapest paint and add brick texture to it. I think they're moving away from the toybox feeling of Sims 3 (amassing glorious wealth and friends was too easy).
2. Open neighbourhoods. Did they really add much? They lagged, all the spaces between lots were bland, and driving was a glorified loading screen (that took longer than the ones in sims 4 most times).
Also, on loading times. They are so much better, the game loads faster, and lots load quick enough to not really bother (unlike sims 2, where you never wanted to leave your home lot because it was a 3 minute load). On a standard HDD (SSD going to be installed in a week or two) it took exactly 30 seconds to load from home to a public lot.
I'll post more opinions when I have them.