Before the 5e Monster Manual came out and all I had to go on was playtest material and previews, I wrote a post talking about how boring and lame 5e's monster design was compared to 4e's. Now that I've had my hands on my Monster Manual for a couple of months, has that opinion changed?
In fact, it's taken a major step back in one important area. In at least one playtest, spellcaster stat blocks included quick summaries of their spells so you didn't have to switch to a whole different book just to see the monster's capabilities. Which was good - that's what 4e did, and it made stat blocks entirely self-contained.
Well, too bad, that's gone from the full MM.
I mean, I guess I can see why they did it - the lich has 27 spells and I assume a 3-page stat block was not something the designers were thrilled about. But at the same time, holy crap twenty-seven spells! You're telling me I have to read twenty-seven spells from different pages of a different book if I want to be prepared to run a lich? What the hell. That's worse than I expected.
On the other hand, more monsters are more interesting than I expected from previews/playtests. Not as interesting as 4e where monsters usually had several unique or tactical abilities, but at least monsters tend to have at least one ability that elevates them above being just a set of numbers.
That said, dragons are a huge disappointment. The five chromatic dragons are literally the exact same stat blocks except for some numbers and breath weapon type. And since they're all so close in challenge ratings, even the number differences are tiny. The legendary actions would have been a great place to add some differences and unique abilities, but those are all the same too.
The book itself is great. The art is fantastic, and there's a lot of interesting flavour text that presents some intriguing ideas to work monsters into a game. But dragons are boring and spellcaster stats suck.