I had a number of issues with the 5E implementation of the warlock. So, let's see...
1. "Invocation taxes." You don't get many invocations, and Agonizing Blast/Thirsting Blade are practically mandatory to be effective in combat. If you don't take one of these, your regular damage output plunges by at least 35% and as much as 50%.
New packet: Thirsting Blade was folded into Pact of the Blade. Pact of the Tome provides the same benefit as Agonizing Blast and they don't stack. Good! AB does stack with a chainlock's familiar attack, not ideal, but okay. But then they turned Mystic Arcanum into an invocation, and it's now your only access to appropriately-leveled spells, and you have to take it again for each spell level you want access to. Also, a bladelock who doesn't take Lifedrinker at 9th is insane.
2. Pact of the Blade sucks without the "hexblade fix." This is pretty self-explanatory, I think.
New packet: Mostly fixed. Except Lifedrinker. See above.
3. Pact magic underpowered and frustrating when short rests aren't readily available. This is really a consequence of the decision to make short rests an hour long. The idea of pact magic was really cool and interesting, but the implementation needed work.
New packet: Pact magic is now underpowered even when short rests are readily available! Also, it isn't cool or interesting any more, you're just a half caster, who can buy your way up to a mediocre full caster by devoting invocations to Mystic Arcanum. What? That's not what you wanted?
4. Poor spell selection. The warlock spell list was severely, painfully limited.
New packet: Fully fixed. Warlocks have the same spell list as all other arcane casters.
5. EB spam is ridiculously better than any other option for a non-bladelock. Eldritch blast is a top-tier attack cantrip by itself, Agonizing Blast increases its damage by up to 90%, and the built-in multi-attack synergizes with spells like hex and invocations like Repelling Blast. Using any other cantrip as your go-to attack is a trap option.
New packet: Partly fixed, but only partly. Hex now loads all the damage on your first hit, and Book of Shadows means you can add your stat bonus to other cantrips... but most of those cantrips get only one damage roll, while EB gets two or more from 5th level. And Repelling Blast is still per-hit. And it's still a top-tier attack cantrip all by itself. Which you get automatically now.
6. A lot of invocations just suck. Armor of Shadows, Eyes of the Rune Keeper, Otherworldly Leap, I'm looking at you.
New packet: Still there. Still suck.
Final tally:
Fully fixed: #4
Mostly fixed: #2
Partly fixed: #5
Fixed and then re-broken: #1
Unchanged: #6
Made significantly worse: #3