The big issues aren't that the game has some tweaks from 5e, changes were inevitable. The issues are the changes to the action economy and the excessive explosive/flammable barrels, and cantrips being better than leveled spells. Eldritch Blast is already incredibly powerful in regular 5e. With the changes to the health and AC of enemies, it becomes the best damage spell in the game.
Firebolt should not automatically light the target on fire, even on a miss. Stealth shouldn't be automatic outside of line of sight. You shouldn't be able to cart around fifty barrels that explode if you look at them funny. Gunpowder is supposed to be rare in D&D, and should also exist for a reason other than to be a bomb in a fight. Hell, oil should be relatively rare in D&D, and a lot heavier than what the barrels of oil claim to be. The size of the barrels looks to be about equivalent to a standard "55 Gallon" barrel. 55 Gallons of water is 460lbs. Moreover, gunpowder isn't explosive except when confined tightly or in large quantities. The barrel should either be too big to move easily, or not be explosive. The barrels should also have more than 1 hp. The barrels of wine should also not be flammable, it takes high proof alcohol to burn, not random ale or wine you find in the wilderness.
Everyone and their mother has complained about disengage being a bonus action. But the fact that it is also tied to jump is also an issue, both because of issues with pathing, and because it negates blocking movement using intelligent positioning. Also piles of surface effects isn't "tactical" unless it's a relatively rare resource. Not all over every single encounter, and not something you can cart around in your pocket.
