I've done it this year with Jas as we couldn't go away in her half term end of May and Mike has a leave embargo from June - October
It was the first and is likely to be the only time we need to take Jas out of school. We cleared it with the school first and they were fine. She has an excellent attendance record though and the only other time she was off school was for 3 days last year when she dislocated her elbow and was in plaster.
She is way up in her class and we have also offered to take work away with us so she can do a bit every day. In fact, although they didn't ask us to do that, we may get her to do a little scrapbook 'project' while she's off about where we stayed and things around there where she can collect information/postcards etc and show the school. They always encourage the kids to tell everyone about their holidays at the front of class when they come back so it might be a nice thing for her.
I think it varies on the school but I would *always* ask first and to be honest, I wouldn't take unauthorised leave for the very reasons Samuel said
