[quote=BROttorney]Need to be able to short rest twice a day. [/quote]
Agreed. Without at least two short rests a day, and possibly more at higher levels, the warlock falls far behind the other spellcasting classes. It's noticable even at 3rd level - it will be a nightmare by level 10, when they still only have two spell slots that can be used twice per day. For comparison, a cleric has 15 spell slots at 10th level, and probably a better AC.