4E fighters are as complicated as a 3.5 caster of equal level?
No, not seeing it. A 10th level caster in 3.5 (Let's say wizard) could cast at least 20 spells a day, plus int bonus, and a 10th level fighter in 4E has 11, plus perhaps a few for magical items, but ditto for 3.5 so no change there.
4E is a lot simpler for all the classes. Spellslinger or not.
Eh. I'd say traditional 4e classes (PH1/PH2 style) range in complexity from about as complex as an extremely low level (say, 2nd or 3rd level) 3.x spontaneous caster (at low levels) to that of a mid level 3.x spontaneous caster (at high levels). They're never as complex as a high-level 3.x caster; they're always more complex than a straightforward beat-it-with-a-sword 3.x fighter or barbarian.