My input is that the wizard out of the box is very very meh class. Almost pointless. Sorcerer and Warlock outshine the wizard in every way.
But, where the wizard does shine, as he always has, is versitility. You can only have 44 spells minimum in your spellbook. Those other classes can only have like 25 spells or so total. Which is fine since you can only have like 25 spells "memorized" anyways at level 20, just like them.
Now if you look at the spell list, like level 5 spells, there are over 20 spells just there. Wizard list is huge. And take into account that you can scribe other spells and you could have 100 spells in your spellbook. There is an enormous amount of versitility in your arsenal.
The downside (and a little too harsh in my opinion) is the gold and time (mostly the time) it takes to scribe a spell. Where everyone else can learn a new language, or a tool or even make gold, the wizard has to spend most of his time scribing spells. Or making a copy of his spellbook.
Now for casters in general, yes, I agree spellcasters got the big axe. You can only cast 1 level 8 and level 9 spell per long rest and I believe 2 level 7s. There are tons of great level 8 and level 9 spells that don't seem overpowered, but pretty good utility spells. And right now, no way of increasing those spell slots.
But the wizard IS a great class, but without a LOT of time, a LOT of gold and a LOT of luck (scoring the spell scrolls) you will not be as great as a sorcerer or a warlock.
Don't get me started on Divine classes....