I currently have a fab one, but have had some duff ones in my time...one ceiling still left to be replaced after the mad sewage pipe blocking/flooding italian!
We have AP+ and I don't work, my Dh works away mostly and my DS has severe special needs - anyone looking down on me would be invited to care for my DS for 24 hours and see how they felt afterwards!
For me a good AP is the difference between (sometimes not) coping with life and enjoying my family.
We live in a big 5 bed house but AP shares a bathroom with DC - although technically she is still showering nextdoor as plumbers finished (installing new bathroom due to flood damage with foulwater caused by last AP) whilst I was on hols and I need to give the travertine one last coat of sealant.
Ours has TV, DVD, wireless laptop, kettle & fridge in her bedroom. She spends her evenings on SKYpe with friends and family although she eats several evening meals per week with DH and I, she has befriended girl next door and they go out together.
She joins in most weekend activities with the family when she is in, although I regularly remind her that it is her day off and ask her if she wants to have some peace and quiet.
Yesterday she helped with plum picking and electric fencing, weeding of ragwort and docks from paddock, hanging out laundry, rounding up chooks, clearing up after meals (I cooked/made all meals), playing with DC. We have just returned from 10 days hols where she did only 2 hrs per day max(animals, her own laundry etc) for full pay so I didn't feel so bad about her helping.
I can't force her not to play with the DC or join me in hanging out laundry, but on her days off I do not let the DC go to her to play only if she chooses to join in with the DC and I.
She has fully 'joined' our family and it feels like having a really helpful 22 yr old DD who is happy to muck in with chores, as are my own DC (they both mucked out, fenced, weeded, picked plums, cleared tables, loaded dishwasher, chased chooks and collected eggs yesterday)
When it works well it is great.