MAN OF STEEL was a complete remake of Superman, done by John Byrne in 1986. Basically everything that had been done with Superman before was thrown out the window and Superman was rebooted from the ground up.
The most common reason people give for liking MAN OF STEEL is that it humanizes Superman, bringing down his power levels and making him more relatable. The most common reason people give for not liking MAN OF STEEL is that it humanizes him too much, taking away the sense of wonder that had defined him for decades.
My dislike for Byrne's take on Superman is related to that, especially when we're talking about his Superman run that followed MAN OF STEEL. You see, I was around four years old when this came out, and I was reading this at the same time I was reading some Silver Age reprints! In those Silver Age reprints, Superman had a Fortress of Solitude in the Arctic, a Legion of Superheroes in the future (along with a Legion of Supervillains!), some superpets, and a bottled city called Kandor. And most importantly, he always won. I get that this "always winning" thing may have gotten old for readers, but Byrne overdid this in his Superman run, when Superman just always lost. I mean, this is the cover of SUPERMAN #1:
I get why they have to knock down the powers, though. There's a fine balance when it comes to Superman, and it does seem that this balance is mediated through the powers. Basically, when he's really powerful, there's an overwhelming amount of charm that no one aside from, say, Captain Marvel can match. But the drama is knocked down because he's too powerful. Knock him down on the power scale though, and you increase the drama but decrease the charm. It depends on the writer. I did an interview recently for a local magazine where I say that basically, there's a spectrum of Superman fans, and it begins with the powered-down Siegel and Shuster "realistic" Superman and ends with the powered-all-the-way-up completely "unrealistic" Mort Weisinger/Otto Binder Superman. I clearly run near the second extreme, and Byrne's take is closer to the first. So it's not like I don't get it; I just think Byrne went overboard with it.
But this is about MAN OF STEEL, and not the rest of Byrne's Superman run, and with the DCnU ACTION COMICS #1 out next week, written by Grant Morrison and drawn by Rags Morales, I'll just go over really quickly what I really didn't like about MAN OF STEEL specifically. And that can be symbolized by one thing perfectly: the birthing matrix.