It really depends on how reliably you can get short rests. If you don't get them that often, you are often stuck with eldritch blast spam, a few free spells from invocations (provided they don't require spell slot use) and your two actual spells. We had a few warlocks early, but now they are "the class you dip into" a few levels and then switch to paladin or sorcerer.
Maybe what they could do is have the recharge mechanic of Warlock spell slots be rest-independent and more akin to a quick ritual? Like “you take 5 minutes to contact your Patron and recharge your mystical energies, recovering your spell slots. You can use this ability a number of times equal to your Proficiency bonus and all expended us are restored when you finish a long rest.”
I would like, if we're going to keep pact magic, is some way to avoid using "spell slot" to cast them to avoid the multi-class problems. If pact magic is going to be a proud nail, it shouldn't interact with other spellcasting at all. No paladin smites, no sorcerer breaking them into spell points, etc. Treat it like monks using ki to casts subclass spells.
I'm totally fine with that. Call them Eldritch Charges. (ooh... make Eldritch Blast inflict more damage the more unspent charges you have!)
the exact oppisist... since you can just blast away with at wills and a few invocations your choice of spells don't matter that much and can be made easier without reading 3 books full of spells
it is so funny how different groups are... I have seen level 20 straight warlocks and never once seen a sorcerer get above 5th without multi.... the sorcerer is the dip class at my tables
To be honest, I've usually treated warlocks closer to magical rogues: you have a few neat tricks you can do at will, but more or less do the same thing every round. (Sneak attack vs eldritch blast). They aren't true spellcasters and shouldn't be considered equivalent to them. Which is why I wasn't sure if they would be converted to full or half caster if they were to move to a regular spellcasting system.
