Nothing mechanical, but it sounds like they are still using quite a bit of monster design from 4th Edition.
Strength in Numbers
In 3rd Edition an orc was CR 1/2, which meant that you would want to throw like, two of them at a 1st-level party as part of their balanced encounter. Given the unreliable nature of Challenge Ratings, depending on your party this number could vary quite a bit. Case in point when I ran Burnt Offerings for three players, they got creamed by a trio of goblins (otherwise known as the first encounter). 4th Edition upped the character-to-monster ratio to a 1:1 basis, with the rule of thumb being that you could swap out one monster for four minions (though I have heard five works better). In this way you could end up throwing a small horde of monsters, better approaching what I felt was a realistic amount.
There are a few critics opposed to the notion of just throwing more monsters at a party to account for their level. I think that this solution is just as good--if not better--than simply leveling up a monster; I would rather my group take on a larger warband of goblins, then just a handful that are inexplicably harder to hit and deal way more damage. I also do not mind the notion that a town can provide some measure of support without having to bump their level up to that of the party's. Besides being able to lead an army or rally a militia that will not instantly die (or just be a pointless exercise in d20 rolling) would be awesome for charismatic characters.
4th Edition gave us the leader role for both characters and monsters, which basically let you know that this thing was good at giving out bonuses/healing/actions/etc to her allies, and I loved it for adding a tactical layer for both sides of the screen: DM's got the ability to buff their monsters and let them do other things, while players got an important target to go after. It also introduced "monster schticks", in that goblins could scramble away if you missed them, gnolls did more damage when you were surrounded, and orcs got in free hits before they died.
Thankfully it looks like they are retaining both of these concepts to some degree, which will hopefully be an indication to 4th Edition fans that they are not just throwing everything out. From what Mearls is saying, DMs will still have a lot of control over how complicated they want their encounters to be, by choosing if you want to include leaders/champions. I am also pleased to see that they are "likely" to add in a rule for breaking away from melee (hopefully also for running by monsters), as well as grouping monsters into units (which makes things go faster and also helps avoid just running through monsters to get to the BBEG at the back).
Not all monsters will be simple, especially those that tend to operate alone. Sound advice, though I hope that "elites" and "solos" will not take a billion rounds to whittle into the ground. I am glad to see that rather than build in hard-wired special attacks to an individual monster, that they are at least considering general maneuvers that a monster can try. This is what I wish they had done with 4th Edition's powers, and hopefully this time around we will not see slight variations on "make two attacks" or "make an attack and knock a target prone".
I really hope that they stick with something like 4th Edition's stat block, as it made things very easy to navigate and read, even for complex things like dragons, primordials, and gods. Go ahead and and include all the "lore" content that you want (personally I dug a lot of those Ecology articles), but do not force DMs to dig through a huge wall of text that then forces them to reference another book to figure out what this or that monster ability means.