My daughter was there until about two years ago, when we had to move her, basically because of the problems you have heard about.
There was an increasing sense that the school was losing control, that there was no leadership, teacher turnover was increasing, and the school did not want to communicate with parents. A lot of badly controlled lessons and a general feeling of unsafety. I think the final straw was when my daughter came home and told me that the girls had been freaking out all day because there were rumours flying around the school that an excluded pupil had made their way into the school and attacked a teacher. I rang up the school and was told that nothing had happened, that the girls had maybe made it up because the police were at the school that day, but 'they're often here' (true - ongoing problems with theft, fighting at the bus stop, etc.) A few days later the story was in the Croydon Advertiser: it was all true. When the council later threatened to close the school, I only found out about this from the paper as well. It became clear that the teachers, governors, and headteacher were no longer working together. After this, the head teacher was suddenly fired.
As with any school, there are some great teachers there and of course lots of lovely kids, some of whom get great exam results. However, I cannot believe that the new head has got the problems ironed out yet. I think it is a shame the council did not hand the school over to an academy as they were threatening to do.
I think you should speak to the head to give them a chance to convince you that they have turned the school round. But ask some hard questions and be difficult to convince. Also, visit the school, in particular around the time the girls leave. And to be honest, I would put down Norbury Manor as your first choice.