Without further ado (and in the order I received them) . . .
This is simply awesome. Monster Manuals are odd beasts (sorry). They are slam full of ideas, but reading them doesn't really flow. Each monster is almost like a chapter, not always related to any other chapter. The art, and graphic design, are phenomenal. The write-ups are fantastic, giving each monster all the space it needs, and nothing more. I grew to detest the 2nd Edition Monstrous Compendium paradigm of "One creature per page". Some of them just don't need that much space. The stat blocks also appear very user-friendly. The stat-blocks in 3.x/4E intimidated me somewhat.
Bounded Accuracy is evident here, in the monster ACs and bonuses to-hit. For example, from the d20 SRD, an Ancient Red Dragon (because, why not?) has the following AC and to-hit bonus: AC 39 and Attack Bonus of +44. The 5th Edition Ancient Red Dragon has an AC of 22 and an Attack Bonus of +17. Of course, there are other points of comparison, and factors that will influence the relative hazards, but I think this is somewhat telling. When we're talking about characters gaining a class-based maximum of +6 to-hit, an AC of 22 is frightening, but not a death sentence. A character could conceivably hit such a beast without benefit of any magic weaponry or other aids. Not advisable, but conceivable.
This speaks to a desire I've had for a while for my games. Characters who are butt naked badasses. They have the potential to be serious threats, sans magic items. I blogged about that in this post. It also means that creatures remain viable threats further into the campaign.
I was already familiar with most of what's in here. The system proper is in the free Basic pdf. This book has more options for characters, mainly in the form of expanded class selection, and optional Feats. I'm not trying to review anything here, or even give details, so this is very subjective. I'm just as happy with 5th as ever following this release.
I haven't really read all of the classes. I like what I have read, though. The Paths idea is awesome, and incidentally, something I postulated in this post. That post is dated from a point over a year into the playtest, and I'm not suggesting that my idea for it was original. My point is that I like the concept.
I love the power curve here, too. The max bonus a character will have to do anything, based solely upon class, is +6, and they don't reach that bonus until 17th level. Of course, there are still bonuses based on stats, and other factors.
Backgrounds are awesome, and make excellent hooks into a campaign. I even like the implementation of Feats (at least on paper). They seem to be a gateway to a more limited (and easier to manage mechanically) form of multiclassing. There are feats that allow any class to learn some magic, or cast ritual spells. Weapon and armor feats for the martially challenged. Skill feats to allow non-thieves to dabble in larceny. All in all, a convenient way to customize a character without having to go all-in with a whole new class.
On a slight tangent, I like this for another reason. I have to admit that I liked the concept of prestige classes. In practice it became a min/max holiday. A frenzy of taking a level here and a level there for the sake of a certain combination of abilities. Meh. This is much better implemented and tightly focused. Many of the feats give almost a prestige-class vibe, without the need to have a character with 4 classes just to achieve a particular vision.
Dungeon Master's Guide
This one blew me away. This book is a work of genius on every level. I don't even know where to start. It is like reading the 1st Edition AD&D DMG, if it was written in 2014. It has so many of the things from the original that screamed "DM!" It even has the old Forms of Government table and descriptions. Totally awesome.
The chief way it differs from its predecessor is that the original included tons of advice on adjudicating your campaign. This was vital when you're talking about a game that operated on the concept of DM rulings being part and parcel of every session. This DMG focuses more on conducting the campaign, rather than handling the mechanics. Set the dials and switches, and start the engine. After that, it's all about the story. The rules hum quietly in the background, always ready to smoothly rise to the fore when needed.
On my very sketchy first readings, one of the things I think is pure gold is Appendix A: Random Dungeons. Tables for generating the maps of a dungeon level, as well as "backstory" type details. My favorite tables are the ones for random environment things. Sounds, smells, room furnishings, random books and scrolls. All completely awesome.
The other part that immediately caught my eye was Chapter 9: Dungeon Master's Workshop. This chapter is loaded with optional rules, many of which have their origins in the playtest documents. So, if there was something you liked that was cut from the playtest, like Proficiency Dice, chances are it is in this chapter. The thing I really like about this chapter is that these options are fully realized. This is not a few words of vague advice, like "Rather than static proficiency bonuses, you could roll a die based on level to randomly determine your bonus." No, no. It is fully spelled out, including how it changes the feel of things. Also included in this chapter are optional rules for Honor and Sanity, both very welcome additions.
There is so much to be excited about with this new edition. I haven't even scratched the surface of what I'm excited about, and I have only begun to scratch the surface of what is offered. If you haven't picked it up yet, run, don't walk.
By the way, even if you plan to run a campaign using the free Basic pdf (which is completely viable), you should strongly consider getting the DMG, at the very least. With the advice in it a Basic campaign will seem anything but basic.