My DD has just come back from France where she was working as an English language 'assistante' in a school for 11-15 year olds.
Financially it makes a LOT of sense. Students who go to work in schools under Erasmus, get paid and, as crazyspaniel says, get a grant from Erasmus as well.
They only ever do part time hours, which is a blessing. It's stressful for most of them at first I think, because a lot is expected of them - they have to draw up lesson plans, and, of course, cope with recalcitrant kids (inevitably, there will be a few of these). That's really hard for students, just as it must be for newly qualified teachers. The students don't get any training to speak of, although there are a few induction days to help prepare them.
But Erasmus iS a great scheme. My DD has no regrets and I think she is quite proud of herself for having tackled something which was a challenge to her shy temperament. She made a success of it and was given a home made poster by her favourite class with sweet little messages saying she had been their best 'assistante' ever, that they'd really liked having her, etc etc. Really touching.
Her French has improved, although she had a stroke of bad luck. Her landlady went into a psychiatric hospital for the entire duration of my DD's second term as an assistante. So, DD found herself living entirely alone except for a dog! - in a big old house (almost a chateau). So, on the evenings when she wasn't going out,she didn't speak French at all!
The hardest thing of all about Erasmus, I think, is that if a student decides to go for the 'assistante' option (they can just do a university course instead, but they don't earn money then) - Erasmus doesn't help them find accommodation. Sorting out accommodation is a big challenge. DD's father and I went out to France with DD before she started work, and gave ourselves nine days to help her get somewhere to stay. It was a nightmare, and we only got her sorted about two days before we were due to come back home. We were seriously thinking we'd have to cancel our return journeys, take extra time off work etc. So the accommodation thing needs to be carefully planned.
A student doing Erasmus but via a university course in the host country, shouldn't face accommodation problems. Invariably (I think) they can stay in Halls.