My son has just started in Reception at Millennium and we're so happy with the school. There's a real buzz about the place. We also looked at Halstow but for various reasons, we preferred Millennium.
A lot of it depends on what will suit your child.
I have friends with children at Halstow and they are very happy there and love the school.
Millennium is very inclusive school -there are many children with additional needs and families from many different cultures. The staff are amazing.
I really like that as a parent, you're made to feel welcomed at the school. We parents are allowed in to the reception class room and the teachers always have time for a quick chat. I know that at Halstow (and most other schools) you have to drop off in the playground. I'm not saying either system is 'better' - it's a personal preference thing.
The Y6 results are coming out soon and I've heard the children did really well (there have been some historical 'issues' which as a local parent, I'm sure you're aware of) - although personally I think there's a lot more to primary school than passing exams. Also there's not a massive emphasis on homework but again that's a preference thing.
Tbh, the worst thing about the school is the journey. The roads are really busy and I do worry about pollution but then no East Greenwich Primary school is in a great location!
Good luck with your decision. I remember last year how stressed out I got by the whole thing!
If there's anything specific you'd like to ask, do P.M. me.