My 2 Cents, which echoes a lot of posts already:

DnD 5e Rules:
Cantrips: With secondary effects on the environment they become more than their original intent. With higher level spells such as sleet storm that actually effect the environment, it diminishes their purposes. Also, while cool for early access to show the effects on environment, not everyone wants the environment to be effected.

Range of spells and of bows: The range of eldritch blast for instance is huge, and while slightly longer than most cantrips, is supposed to encompass a huge range. Same with bows. It diminishes the use of stealth characters that want to pick off enemies (like in the goblin town) and then go back into stealth. Which brings me to my unique point, auto stealth. If you are in a surprise round situation and the enemy fails a perception check, having an option (similar to a toggle like opportunity attacks) to immediately pop back into stealth would be helpful. Rather than relying on pressing c and then needing to move.

Adding modifiers to damage. Please fix this!! Nothing is as annoying as having a +3 strength fighter and not being able to deal damage similar to spells. Imagine a 2 handed battle axe hit dealing 1 damage and this dude hits you with a little bit of fire and you take 6 damage.

Stealing: As a rogue pickpocketing is a staple. However, when someone immediately comes to you after stealing (despite the fact that you have blessing of the trickster AND were invisible when it happens) and starts blaming you causing all the tieflings to attack you, its a little annoying. (for this reference I actually unchained my player rogue, sent my party to the entrance of the enclave, and still wasn't able to get away with it.

Have the shove actions, jump actions count as their appropriate action economy. Jump doesn't take an action but there is a success fail. Shove is an action.
Give us a grapple option!!!!!

Auto sneak attack damage please

For mage hand ledgermain can we get the option to pickpocket and disarm traps

Can we also get the ability to cast touch spells out of our familiars and our invoke duplicity trickster clerics. It's one of the things that makes trickster clerics awesome

Can we get options on starting equipment? I realize that we are prisoners in a mindflayer ship, however, the option to pick up our equipment along the way would be great. (make it part of the story, you kill someone for equipment, or you an intellect devourer brings you something?)

Give us the illusion of control with the dice. If we have advantage/disadvantage during dialogue checks, roll 2 dice.
Give us more dice checks then just in discovery/dialogue mode. (ex, when jumping down give us an acrobatics check to not fall prone, give us survival checks to locate plants nearby, nature checks to see if the weather is going to change,)

Expertise with Rogues!!!!

Fix starting class proficiencies with weapons/armor

When it comes to backgrounds, there is usually a feature attached, perhaps giving a feature or a unique feat to each background
Backgrounds also let us pick additional languages we speak, that would be helpful
Acolyte is in service to a God, let us pick a god that would affect dialogue

Give us the spare the dying cantrip. It'll reduce the need for revivify scrolls.

Give us options on spell casting - colors, flavors, casting stances
Give us battle stances/poses
Let us pick an alignment. Give us options based on that alignment, while also making it fluid. Are you a L/E rogue who keeps helping people. Move to L/N. Etc. Allowing us the freedom to act out our character in dialogue is key DnD 5e stuff. Giving certain options based on alignment is just as cool as a tiefling option. Or getting whispers (that guard looks like he's got a lot of gold on it, want to steal it?) would enhance the roleplay as well as give unique moments for classes.

Game Play Fixes:
Fill loot in places or remove clutter
Give us lore!!!! Use books to give information etc. Can add more history checks for details, and make languages useful.
Make traps more strategic. Having one room full of traps and then having traps almost no where else is boring.
Remove barrels from the game. This isn't DoS. There are way better ways to make things happen. In a cave, someone's gotta have an oil flask for lanterns. Burn that.
Make use of climbing. There are plenty of cliffs and walls that would be a great place for grappling hooks and climbing gear. More dice checks too!
Have enemies also roll stealth. Having ambushes in goblin town was awesome! But in combat watching a goblin rogue stealth would be great.
Health Bloating! Goblins don't have that much health. (As a side point to this, I love how long combats are and how much tactical thinking goes into this. Its awesome keep that up. But instead, find creative ways to bring more goblins in OR a reason that their hp is so high. Also, this would be fixed with modifier damage)
Use languages. Goblins communicating in goblin are hard to understand. Have them give commands to each other and only if you speak goblin do you know what they are saying.
Warlocks have a patron. Give us some information or options for how/why we are warlocks. For that matter give us more information in the story. Where did we come from, why are we the background we are, etc

That's all I have for now. I'll post more later!

Finished act 1 as: