Dislaimer: I really like 5th Edition, but that doesn't mean I don't have some critiques, some of which may even be subjective personal taste. This is not an "I hate 5e" or "D&D 5 is completely broken" post, so don't take it in that vein.
Excessive healing appears to be a pretty frequent complaint of the old-school community. Hit Points are abundant in the new edition which appears to come largely from the 4e encounter design ethic. The idea is that a party will (or is assumed to) come into any encounter with mostly full hit points because they have spent short or long rests preparing. I understand this game design ethic (even if I personally don't agree with it) because it means a DM does not have to make any assumption on how hurt the party will be walking into an encounter or that the party will even have a Cleric. From an encounter design standpoint, the DM should assume that the party will have most of their HP at the beginning of any given fight. Hit Dice then become the out-of-combat resource to manage as you only get a limited number back after a long rest, but many on the internet appear to believe that this isn't hard enough on the PCs.
I do think the healing is a little too prolific for my own tastes, but I'm not up in arms about it. I will play the rules as written until I think I have a reasonable compromise. For my own game, I will likely house rule that PC hit points are not fully regained after a long rest which will make Hit Dice even more precious... but I need to test this out in actual play.
On a related note, +Venger Satanis offered an idea on lasting/severe injuries that was pretty interesting. I'm going to write up my own take on his suggested house rule in a separate blog post, as I wanted to incorporate his idea into some of my own on house rules for injuries and healing.
Level Advancement is way too fast through through to level 4 or 5. Levels 1 through 3 pass by in an eye blink. I do not like this at all. It's easy enough to house rule for my own game, but if I'm not the DM, I have to live with this super quick pace.
The design philosophy that a character should level up every session for the first 3 or 4 sessions makes no sense to me. Low level play is a lot of fun and I'm not sure why the game designers want to rush us past the danger of these early levels. It's as if they are saying Levels 1, 2 and 3 are "less fun" so let's skip past them. If that is the case, then why start at Level 1 at all? Why not make Level 3 the default starting level? Or instead of making these levels rush by for everyone, why not make 1 through 3 go more slowly and use quick advancement as an optional rule rather than setting quick advancement as the default?
I'm not sure why I'm so annoyed with this, but I really am. Perhaps because levels 1 - 5 are my favorite part of the game. Exploring a new character as a novice and finding his personality is important to me. I do not want to rush through all that just because the designers think we should get to Feats and Ability Adjustments sooner. Lame.
Cantrips do too much damage. In my mind, a "0 Level" spell should do something like 1-6 damage at most... Ray of Frost does 1d8 and Fire Bolt does 1d10. Why are they different? Why not make a generic "Elemental Bolt" which could manifest as a specific type (frost, fire, rock dagger, etc) that all do 1d8? Or 1d6 plus some other side effect (like the slowed movement)? In the early levels, there is little chance you are going to face a creature with fire resistance, so why would anyone pick Ray of Frost over Fire Bolt? That 10 feet of lost speed is nothing. Now if it limited the creature to only 10 feet of movement at all in the next turn... But then that would also be way too powerful for a Cantrip. Cantrips should be fixed, but I know they probably won't be. Bummer.
So this might be a dumb personal peeve, but let's get rid of Studded Leather and Ring Mail. These are stupid armors that had no historic equivalents. I'm not even sure how bedazzling your leather armor is supposed to help. Add in real historic armors like Brigadine in their place. At least Banded Mail has stayed dead.
...is utterly broken. A STR 10 peasant can carry 150 lbs with ease and lift 300 lbs. Wha?!? The encumbrance variant is a little bit better, but the baseline needs to be redefined. 10x/20x STR would still be high, but much easier to swallow for game purposes. Using the revised factors, a STR 10 peasant could then carry 100 lbs and lift 200 lbs. I see this as a reasonable compromise for the purpose of a non-simulation game.
According to page 60, your PCs are going to look like this guy.
There has been some criticism on the internet about rewarding role playing mechanically. I don't see a problem with Inspiration for reasons that probably require a much longer blog post. Bennies of one sort or another have been around for a while in numerous RPGs. Look for more on this from me later.