I love my guineas! I lost a few of mine to predators late last fall so I currently have one adult and 4 keets soon to go outside. If you want a bird that's interesting to watch, does a great job at controlling ticks, they're great. I got mine because we had a horrible year with ticks - I had 5 on me most days, but I haven't seen any in awhile after I got the guineas. Could also be the chickens.
They're very noisy, especially females. I haven't had any weird behavioral issues from mine, she sleeps with the chickens and has never acted out towards them, gets along with the pig etc. But everything deserves an alarm. New stick in the yard, new coat on. It's lessened over time, and she has alerted me to hawks and cats but most of the time she just lets me know that it's me she's screeching about.
They're not as friendly as chickens, even as babies. I've had them from 3 days old, and had them from 5 weeks old and neither have made a difference as far as handling. I've seen some people have loving guineas but mine aren't haha.