as others have said, it's really that they are COMPLETELY dependent on
you- no one else is going to care for them as well as you do.
most people just won't understand what you are doing. that means that no matter how excited you are about how big your chickies are getting or how many eggs they laid, no one else (except the people on here maybe
) is going to care, especially the 3rd time you tell them.
most people aren't going to be willing/able to look after them if you go out of town. there are TONS of people i know who i would trust with my dogs and cats. there are maybe 2 i would trust with my chickens- only 1 of which i would trust with chicks. most people aren't going to realize that when you say the chickens HAVE to be let out at 7:30 EVERY morning, that you actually mean HAVE to. it's not like a dog who, worst case scenario, will poop in the floor if you aren't up. stress from being hungry or thirsty can really affect their health and their egg production. oh, that's another thing- don't make it out to collect eggs and the chickens might crush them or eat them. chickens who start eating their eggs are NOTORIOUSLY hard to break of the habit.
mostly, it's hard to drag yourself out of bed at 7am on Christmas morning to walk the 1/4 mile out into a field (my chickens are in a mobile wagon), in the snow, to feed and water... only to realize that you forgot to empty the waterer the night before and it is now frozen, which means you have to walk it back to the house, de-ice it, and carry it back out. by the time you get back, you are too cold and tired to feel like opening presents... but you have to anyway because the family is counting on you.
even with all that, i wouldn't trade my chickens for anything... except maybe more chickens! they are fun and rewarding and, yes, extremely addicting. whatever you do, build your coop about 2x as big as you think you need. you will almost surely end up filling it.
in my neighborhood(not really we live on a farm...but we do have distant neighbors)!!!(LOL) Soo...you wanna know the funny thing about it is that I don't care and I'm lovin every minute of it...along with my boys! We just get sooo many hours of enjoyment out of them. They all free range during the day and we lock them up at night. My 4 yr. old loves collecting the eggs in the morning before breakfast and letting them all out to free range for the day(so that's not an issue). My neighbor loves collecting the eggs if we go away and she gets to keep them so who doesn't love free eggs! We went away for a week in Dec.(when we got the HUGE 3ft. blizzard unknowingly) and they made out just fine! They were snowed and their water was frozen but they just ate the snow! I keep a large rubber bucket of water in their barn and another large bucket of feed and it lasts well over a week. If we go away I just leave their trap door open(I know it's a risk) and they go in and out as they please. They are the easiest cheapest outside pet that I honestly know of. My little roos are a riot and even though they can be fiesty with each other at time it's still hard to decide who we want to rehome...b/c they are so cute! I keep hay in our barn and in the hutches that are attached to the chicken tractors and change it once a month. I just added lanol.stick tyles to the wood floors so it's even easier to keep clean. They are really self sufficient little creatures and have just soo much personality and charm about them! I can't imagine my yard anymore without my sweet chickies all running up to us and wanting to be petted! WOOOPS! Was I supposed to give you a con??? 
Oh yeah...I'll go with addicting like everyone else! Blessings,Keri
