btw the carrying capacity perk requires 3 perk points be spent in pickpocketing.
Personally I think the last 2 perks are good, but silly. It just breaks immersion being able to strip someone of their armor without them knowing.
I also understand the purpose - its for people who want to give themselves the edge in battle. Strip someone of their weapon and bam, you suddenly won't be so squishy against them since they wont have a weapon to hit you with.
Or strip them of armor and bam, your attacks will be stronger.
And also, it lets you steal much better. HOWEVER, quicksaving and quickloading still trumps this. There's still a % chance, so you're going to be quicksaving before you pickpocket anyways, just out of habit.

Finally, how good this skill is entirely depends on what Bethesda places in NPC character inventories. If they've got crap, then it'll be a bad skill. But if they carry some rare stuff, then pickpocketing might be useful.