There is definitely a Maidenhead contingent. One of the parents is a forum member so hopefully will be along to give you a local opinion.
My DD is in Y7 so too soon to say whether it is 'worth the effort' but we are happy so far and DD has settled in well. We went to the Open Evening when she was in year 5 but that was in the autumn so I'm afraid you've missed it until next October. It is probably fair comment to say that they don't 'have to try hard'. There is a Spring Fayre on Sat 13 March which I would think you could turn up to for an informal look around? Not sure of the details yet.
Feel free to ask questions!