Been 5 times it is great.
Done normal camping, the pre set up bell tents and staying off site in an air bnb (I was 6 months pregnant that year).
Good things
seeing massive stars you never normally bother to see but who are ace eg Dolly Parton
the daft acts in the corner of a field you'd never plan to see but then become highlights
the food is a real highlight every year. I love visiting the hippies in the permaculture forest bit for a bit of a homemade vegan treat round the campfire.
the art installations in the heaven/ hell dance bit are always really impressive.
seeing stuff you'd probably not bother with normally eg the stuff in the circus field.
the guilty pleasures disco on Thursdays is always fun at Williams green
Bad bits
It's physically hard. Really hard. The walking I can do but standing watching bands/ waiting for bands does your back in.
as others have said if it rains you can't sit anywhere. Very tiring.
carrying in your stuff is really hard too. You probably drag it a good 2 miles at least from yr car.
you can get stuck in human traffic jams it's not all the time but sometimes it can get annoying.
it's pretty gross. The toilets, no showering trudging about in mud. You barely sleep. I find as long as I maintain a slight cider buzz all day I don't mind it though!