One of the main things that they are not implementing well for the Warlock for the special pact abilities. That's where the real power of the Warlock lies.
Pact to the Blade, for instance. Wyll should BE a Pact of the Blade warlock by default because he wields a rapier. Larian stripped the value of that pact by making him a warlock who is proficient with that weapon but not part of that pact. Regardless, there are special abilities like the one that allows someone with this pact to get an extra attack just like a fighter would once they reach level 5, I believe.
I'll stop there. I could go on about all the special abilities for each pact, I would take all day. My daughter plays a warlock currently at level 6, and she is pretty tough.
