Quick version:
If you like Metallica's work since the Black Album, you will like Hardwired. If you don't; you won't.
Longer Version:
Hardwired is probably Metallica's best post-Black album release; but that is a hour late and a buck short. If they had released this in 1991, and then none of the albums that came after, I'd be happy. The music is aggressive, the production is better than on most of their recent releases, and the songs are a manageable length. That's the good.
The bad is that Rob's bass is still too far back, doesn't sound very good, and he isn't being allowed to realize his full potential. The drums are still a little loud and the kicks are pointlessly piercing. Then, after four songs, you really have heard the whole album. There aren't a lot of diverse musical or lyrical themes being explored, so they all kind of blend together.
For me personally, I just don't care anymore. In recent interviews James has made it pretty clear that the change in the bands focus wasn't accidental, and that they made a decision to go a little more mainstream. That doesn't work for every band, and kudos to them for rounding that corner so they could become one of the most recognizable metal bands in the world. Cool. However, as a consumer, I'm not going to get on board. I've been burnt too many times by them and don't want to take a musical journey that leads me somewhere I don't want to go. When a band changes, I've learned to just let go. Opeth, The Sword, and Metallica- sorry but I just can't take that ride.