Depends on whether you want to go social, or dominate in battle.
The former just takes high Cha and lots of ranks, and maybe a synergy bonus or item. It'll make NPCs (the equivalent of) friendly, which may save you cash, provide you with information, open some doors for you etc. Beware the backlash when the target forgets how scary you were and gets all hostile, and you should be fine in many social situations.
Domination in battle takes a bit of work, and will usually only be worth it if you incorporate intimidation as a center part of your build. You'll either have to spend some feats and a skill trick, or make heavy use of intimidating magic. Make sure your opponents can't run away with your loot, and this can be a powerful tactic.
Basically, don't just look at the skill and think "cool!". To really make use of it, you'll have to invest quite a bit of time.