Aside from some minor--but needed--tweaks to the beastmaster ranger (1), the errata looks like piddly stuff and clarifications so don't go in expecting to be blown away by some bold new design choices.
When it comes to errata and redesigns, I think everyone has their particular hobby horses. Personally, I would have made a few more daring changes (2), but I understand why they want to avoid turning the errata documents in a 5.5 version of the game.
Even so, I know what my big change would have been: two-weapon fighting. Here's what it would look like in my errata:
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When you take the Attack action and attack with a light melee weapon that you’re holding in one hand, you can can make one additional attack with a different light melee weapon that you’re holding in the other hand. You don’t add your ability modifier to the damage of the additional attack, unless that modifier is negative.
If either weapon has the thrown property, you can throw the weapon, instead of making a melee attack with it.
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What's changed? Attacking with your other hand no longer costs a bonus action; instead, if you meet the requirements, that additional attack is folded into the Attack action itself.
Why make this change? The two classes designed and themed around two-weapon fighting, the ranger and the rogue, are actively disincentived from using two weapons because of the action economy. Rangers and rogues have too many things competing for their one bonus action per turn. In the best case scenario that would lead to interesting choices for the player to make, but in practice it feels like two-weapon fighting and the classes who need bonus actions to do their thing were designed by separate people on the 5e team.
Does it break anything? I started accidentally using the above revision of the two-weapon fighting rules when I simply forgot that the additional attack needs a bonus action, and so far nothing's felt noticeably broken. Maybe it's a little more powerful in the early levels because it gives you an extra (though less damaging) attack before 5th level, but it seems ok.
Here's what I've noted:
- Two-weapon fighters get another attack if they use Action Surge, but it's still not in danger of overtaking two-handed weapons as the optimal choice for damage in the long run (3).
- Crit-fishing champion fighters and barbarians benefit just a tiny bit from the change. That;s okay with me.
- Rogues and rangers feel like they get to use the abilities that define their classes.
(1) - None of this will "fix" the ranger for people who don't like the class's design, of course. To be honest, the worst part about the ranger is that it has a deadly boring 1st level. Who thought it would be a good idea to front-load the class with two "ribbon" abilities?
(2) - Design changes I would make, that just so happen to look exactly like my house rules:
- I would also have added more spells to the sorcerer's column of "spells known."
- The PHB ranger archetypes could use some additional spells known, much like the archetypes published later have.
- I'd also have initiative rolls use either Dexterity or Intelligence.
(3) - At 1st level, I estimate that the difference in damage between a fighter with the great weapon style and the two-weapon fighting style to be about two points--hardly game-breaking--and once 5th level extra attacks come into play, things move toward great weapon fighting gaining an almost three-point lead. Again, hardly game-breaking.