Mainly positive.

You had a lot of work to do, but you got paid well for it.

Negatives - a lot of work and reports - this should be expected in summer schools.
Some tension between the activity guys and the teachers due to amount of work and pay, but if you speak to the bosses it will be resolved (the standard teachers do nothing, yet get paid more) - not much you can do about this, we just joked and said 'so become a teacher and you'll get more money' or 'life's a b****'.
The DoS was nice, although a little unprofessional at times.
As a centre manager you'll probably have problems - ours left two weeks before the end (we still areen't sure why), and we heard this had happened for the last few years, which seems a little strange.
There is no drinking on site - understandably so.

Positives - they were fair.
We wrote Scheme of Works, and registers; that was it - much better than most places.
We had a BC inspection, so we had to be observed a few times and the Academic Manager met with us and gave us feedback and helped us prepare.
The IELTS programme has been done for you - no work for you to do, but print the materials - a very well written course too!
You get a day off a week, and you can leave the night before and do what you want.

Overall, this was probably the best summer school I've worked for. The only annoying thing was they were all a little arrogant - they thought they were the best and that they were all amazing up-to date teachers - a little silly. If you can live with that, it's probably one of the better summer schools out there.