We have piggies and I ADORE them.
As already mentioned, please do not get piggies for a child. As long as YOU are prepared to look after them then I would say go for it!
I would say, however, that they are NOT easy to look after. In my experience, Guinea Pigs are
extremely delicate creatures who can go downhill very quickly.
They do not really enjoy being handled on the whole. They like lots of places to hide and feel safe and they can be difficult to catch. I have NEVER been bitten by a piggy and I have owned them for 13 years.
Like rabbits, they require company of their own kind. 2 males can get on if they have always been together or if you have a baby boy with an older male. Females get on quite well, although can have little 'squabbles' occasionaly.
We have 2 groups of 10, each with 1 neutered male and 9 females. We also have 2 pairs of boys. Or groups get on GREAT and they are a delight to watch.
All in all, I think Guinea Pigs are wonderful little things. They are cheeky, chatty and funny and, although they can be stressful when poorly, I couldn't be without them in my life.