I've played a lot more of this than I should have over the last few days. My Wizard is cruising through Nephalem Rifts on Torment 2 at this point. They've gotten a lot of things very right.
The Mystic seems to compress the range of high-end items - there's no effective difference between a perfect item and a nearly-perfect item, and half of your drops can be turned into fantastic items, so you end up with nearly-optimal gear very quickly (aside from getting specific legendaries). Gems actually seem like the way to get into the higher Torments; stats on gems in armor sockets skyrocket once you start upgrading from Marquise such that Diamonds are finally not obviously the best choice. Gold is the limiting factor on almost everything. I started the expansion with 14m, and that pretty quickly vanished given the rate at which gems drop. Now I sell all my magics and rares instead of salvaging them. Forgotten souls are also really valuable. Death's Breaths become pretty common once you get done upgrading all the crafters.
Most of the legendaries don't feel very interesting. They're just rares with slightly higher numbers on their affixes. As far as I can tell this sort of crafted/dropped super-rare is still limited to a 4/2 primary/secondary split too. As such, it feels really important to get at least a legendary weapon with a strong special effect (I'm using Shard of Hate right now).
Blood shards are kind of useless past the first few hundred of them you get. You use them to get good rares for slots that you haven't found much for since hitting 70, you use the Mystic to turn those into great rares, and then you're basically done with rares. Yesterday I went through all 500 of mine gambling on orbs and didn't get anything better than the rare I had. "Double blood shards" on bounties is a joke; you get a couple per bounty but then you get 50+ for beating a Nephalem Rift. So just do bounties wherever you want.
I really like the Nephalem Rifts and really appreciate the random environments and enemy types. The random color filter is often pretty ugly, though. The conduits (super-shrines) are mostly really neat, although some are much, much better than others. One in particular is a really satisfying win button. There are a huge number of possible bosses for the Rifts who mostly seem to have unique attacks, and then they explode with tons of loot.
Edit: Oh, and I'll add that I quite like most of the parts of Act 5 too. I strongly dislike most of Act 2 and Act 4, and the end of Act 3 gets super-repetitive, so it's nice to have fun areas to run through beyond Act 1 and the beginning of Act 3.