Yes, he gets SA on all applicable attacks.
Picture this: high-level fighter/rogue with BAB +16 (four attacks), Combat Reflexes, Expert Tactician and Opportunist... and
haste.
Surprise round: one sneak attack plus Expert Tactician.
Round one: if you're still flat-footed, take
six 'normal' attacks with sneak attack, including one from Expert Tactician...
Even better, throw this guy a longspear and have him tumble to the far edge of the fight where he can flank just about everyone...!
Now, as to the balance of this, imho it's fine. Without what lil combat ability sneak attacks render up to the rogue, he's just a distraction in combat. There are a million limits and defenses against sneak attack, too.
I believe the designers have stated that the game was balanced with the idea that the rogue would be getting his sneak attack on virtually every attack. Thus all the defenses against it.
