Improved Initiative is actually campaignDM dependant.
I played in one game where every encounter was an ambush, even when we saw them coming from like miles away Almost everyone had Improved Initiative. In more imaginative games its less useful.

Why has no one mentioned Shield Proficiency ?
Or Simple Weapon Proficiency ?
Or Martial Weapon Proficiency ?
You normally get these as class features, but you can take them as feats; not that I'm aware of a class which doesn't get, at least, Simple Weapon Proficiency.