JackOfAllTirades
Explorer
Agreed. They should have publicly playtested all the classes. It's not a bad skeleton (and is in fact what I would use for a warlord), but it feels like a lot of dead levels and many of the invocations are just terrible.
I just want to point out that the Warlock has exactly zero "dead levels" due to their excellent retraining opportunities. Every single time they level up, a Warlock can replace an old spell with a new one of the highest spell level they can cast, as well as replacing an old invocation with any new invocation they qualify for at their new level. So if there's something that isn't working out like you expected, or a spell that used to work at lower levels, but not so much at higher ones, or you need to free up a slot for something better, or you thought of an awesome idea for a combo next level... whatever.
I'm hard pressed to think of any other class with that kind of per-level retraining flexibility. As short as his spell list is, my 7th level Warlock has just as many 3rd and 4th level spells as our party's Wizard because I've continually retrained lower level spells for higher ones. (In addition to new spells learned at each level.) I think I'm finally about to fall behind. And of course, my 1st and 2nd level spells are mostly gone. I kept Hex and Suggestion, cuz I'm not crazy.