We did buy a new Roomba in an effort to keep up with all of the dog/cat/people hair in the house (I would have to spend an hour vacuuming every day when I got home from work and that was NOT pleasant) and so far it has worked well.
We named her "Audrey" after the "Little Shop of Horrors" plant because it gobbled up the tumbleweeds of dog hair fairly well.
She's definitely quieter than our regular upright vacuum, but not so quiet that I could run it while I sleep. Typically I'll run it when I get home from work for the day and I can do a few other chores while it's running. She does miss a few clumps of hair here and there, but overall it's better than me having to spend the time vacuuming.
It didn't come cheap - $350 for one of these on Amazon, but we decided that with 2 cats, a labrador and two people, it was worth the cost to not have to spend the time vacuuming every day. Our upright vacuum is on it's last legs anyway - we mostly just use it for upholstery.
Overall I'm pleased with it - as it does save me the time/energy of vacuuming and keeps my floors relatively clean. Now - only if I can convince Garry that we need a Scooba (the mop version) we'd be all set!