Me! I know!! Well, not direct experience but I have been to an Open Evening. My friend's mum passed away right when she was having to make all her son's Year Six decisions so I spent some time visiting schools with her and listening to her make choices as her mind was all over the place.
Brentside is in a new and amazingly modern building. Great playing fields. Right on the Brent River Park Footpath. Library is fantastic, nice halls, etc.
It still has a bit of a bad reputation locally. My understanding is that this is largely because the next nearest school, Drayton Manor, was the grammar and Brentside was the Secondary Modern and the relevant labels have stuck.
I also went to Drayton with my friend, and also to Elthorne. Of the three, I liked the Brentside head the most and also found the teachers the most actively engaged and interested in hearing about my friend's child. Her child is highly able at reading and maths, but his primary have not really helped to encourage or push him. He is also an extraordinary artist, which they also don't foster. He is actually bored and glum at school right now. The teachers at Brentside were so sympathetic to his plight, and already brainstorming and plotting all the things they'd do with him to cheer him up and push him on.
They also have more hours in Maths and English per fortnight than the other two schools and smaller class sizes as the teachers have more contact hours.
The Head won the 2010 national Headteacher's award. Their results have been going through the roof since he got there.
I also liked, for example, that all the displays were by the children. At Drayton they looked much more professional, but they were done by the teachers!
I know that more people locally who could choose between Brentside and Drayton, are actively choosing Brentside. It is what my friend went for in the end, and I could totally understand her choice.