I watched the 3D Blu-ray back to back with the original the other night, although I saw the 4K Blu-ray a couple of weeks back too.
Personally I would say the 3D is pretty similar to the original; A nice sense of depth throughout, but not a huge amount of pop-out, and no gimmick shots. Most of the better stuff takes place during the fight towards the end. If you like 3D, you'll enjoy it, but it's not something you'll be demoing to convince people what they're missing out on. It's not like recent 3D Blu-rays have been terrible, but most of the more impressive titles were done years ago; there just isn't the desire by studios to really spend much time/effort on this, unless you're James Cameron. Truth be told, and as someone who loves 3D, I think the 4K Blu-ray impressed me more here.
As for the movie, I loved it. having watched the original for the first time in ages again, I still prefer it; it's a much tighter movie, the cinematography is better (imo) and the JNH's soundtrack is incredibly good. In fairness to Geoff Zanelli, trying to top the original's score was always going to be very difficult if not impossible. It's mostly a "JNH's Greatest Hits" score; re-using lots of his cues from the original movies, but expanded upon. There's original music though and some of it is really good, so I've no complaints there. One thing that did surprise me was the humour, it's much more light-hearted in places than the original, which is no bad thing, and it works for the most part. Maleficent has some great lines, it's just a shame we don't see so much of Diaval or the Fairies. Michelle Pfeiffer was a highlight and the visual scale of this film makes something like Aladdin (2019) look like a Broadway Musical production in comparison, they did a great job there.