Let's examine bestow, the new creature/aura mechanic in Theros.
One of the very first things a person does when absorbing a new idea is to compare it to the things she already knows. For Magic players grokking bestow, the two most obvious comparisons are the Licids from Tempest block and the living weapons from New Phyrexia. WotC was happier about the comparison to the popular mechanic and less so the ugly, complicated one, and rightly so.
I've mocked up what Calming Licid would look like in the modern frame with the latest Oracle text to compare it with Leafcrown Dryad. Perhaps surprisingly, bestow is a textier mechanic, but the language is also more accessible and the overall mechanic leads to a card that's much simpler to process in play. Not only can Leafcrown Dryad not change states simply by tapping, but when it does, you don't have to think about the other state at all, because it's exactly the same as what the aura did. This is a huge win.
I think I've seen people claim that they're too similar, but for my money they're not because they each travel in opposite directions: For living weapon, you get the creature first and the equipment later. Bestow (when you use it) gives you the aura first and the creature later. That you can skip the aura phase entirely gives you another mode with no analog in living weapon.
To explain how much I love this solution, I have to make a final comparison that only fans of Magic Design will recognize. Bestow is the end-result of the Manifest/Incarnate exploration that started (perhaps) with the GDS2. What we were looking for was a way to make auras a little better by mitigating the problem of drawing one when you have no creatures to cast it on. Bestow delivers exactly that.
Jonathan Woodward's version let you cast your aura on a free 0/0 token and is functionally indistinguishable from living weapon, beyond the obvious aura/equipment difference. I don't know if they got the idea from him or not, but he and the community that helped with that idea can be proud they found one of the very best solutions regardless. My version piggybacks off of morph technology and is much less elegant, though not completely devoid of merit: It feels nice to put your 'useless' cards to good use, and starting at 2/2 opens up a few more design paths for the cards.
I can't close this examination without addressing the fact that a bestow aura becomes a creature instead of going to the graveyard when its target disappears before resolution. Obviously, that's a great thing because it cancels one of the biggest drawbacks of auras. What's unfortunate is that the reminder text doesn't allude to that fact at all, and players who know that normal auras die this way will assume bestow auras do too… until told otherwise. Wizards has defended the incomplete reminder text by pointing out that it's not the first keyword that you have to read the rules to fully understand, and that casual players will assume it works because they assume everything works, while experienced players are all tapped into the data stream and will have heard the clarification before the Prerelease. They may be completely right, or only partly right, but I still feel like the ball was dropped. It's a tiny ball, mind you, and not remotely a big deal, but when you're performing on the level that Wizards is, you're playing a game of inches. It's ridiculously rare that R&D makes a sizeable mistake (relative to the amount of product they produce), so if they're going to find ways to improve, most of them are going to be tiny. I'm sure some folks at Wizards haven't dismissed the concern about bestow's reminder text, and hopefully that'll push the next product from 99.01% flawless to 99.02%.