in addition to all these good points, i find the best benefit of having the poles is my hands don't swell -- when i hike without them, my swinging arms lead to swollen and painful fingers and hands - and when i have my hands wrapped around my poles, i don't have this problem.
not to mention the fact that when you're scrambling DOWNhill - it's like you're walking on all 4's - i love(d) mine. i had 2 pair of the cheapo's from walmart (swissmade red one's). one pair got "accidently" stolen - bummer - the following month, while readjusting the height of one of the remaining pair, the twist lock broke and now i am down to 1 of 4 poles. bummer. for $20/pair, a good investment for my earlier hiking days...
in the future, i'm looking to upgrade to a pair with snap locks (like black diamond) but i want the 15-degree angle (leki) and cork handle (less slippery when sweeting). done my research, now waiting for the right price...and for the newest leki to come out in march, from what i heard - they're introducing their own snap locks....definitely want to check them out.
overall - grab a pair of cheapos - not much investment if they only last you a few trips - and try not readjusting them too much - then when you hike without, if your hands hurt, you'll invest in a nicer pair.