Only started playing the beta around the time the control issues where fixed, so can't really comment on issues before then... If you're going to make one piece of a class kit unreliable in a common situation (indoors/tight passages) the rest of the kit needs to make up for it.
As it stands Illum has no defense outlet except for its Ultimate, and the Special attack is far too slow to be used as a DPS/bulleteater option. So in most tight situations you're stuck with the option of:
- snake spell shenanigans
- block using your Ultimate
- suicide rockets, using your invisibility window to AoE enemies
- hoping to land a hit with your slow, tiny Special
That's a pretty rotten deal. Even if Illum's Primary gets a damage, AoE, and/or cooldown nerf, its Caliber does need a buff.
EDIT: @Panopticon. I totally understand what you mean
. Its AoE is quite useful as a pinger over long-ranges without drawing enemies towards you, but outside of those situations, Illum is horrible in tight mid-range situations and the snake/flare require a lot of skill to be used to get hits on small targets & bypassing projectiles.