My mother grew up in Sible Hedingham, my father partly grew up there, basically my mother still lives there with my sisters and my nan lives in Castle now..I grew up between Castle, Halstead and Sible..
Sible Hedingham has had alot of new builds however they have not built new schools or doctors, St.Peter's from experience and placement isnt the best primary school, it was overcrowded, children who were not 'clever enough' left behind, I think the only positive was the Christmas plays, they were fantastic! Some of the school is Victorian, it also has a swimming pool...The school currently has alot of fencing around it, before it was more open, we could literally walk out if we wanted to, it's a positive but it was a shock to see..As for Alexandra road, I grew up there, my mother and sisters still live there, it is a mixture of privately owned and council, Sible did have issues with teenagers but we are talking back in early 2000s, it wasnt the fact the road was dangerous or filled with people on benefits as such, even when you posted in 2012, the street had no issues then but I will say there has always been issues with rats there and damp in alot of the houses..Just Alexandra though as far as I'm aware (just a side note my nan and aunt lived on that road, mother grew up there and my other nan also lived on that road)..
There is a few shops, nothing fancy and a pub, alot have closed down..
There is beautiful places to walk, the history is amazing though some parts sad, there is some lovely old buildings and a mill there.
There is a FB group that you can ask locals questions, they are trying to bring back the community spirit and its doing very well!
As for Castle, I guess it depends where you are, it has richer areas, the Castle is pricey on event days but the grounds are beautiful, I actually learnt to walk there, Castle is a very pretty place but it does lack street lights in alot of areas, there is one shop, I wouldnt say there is as many places to walk as Sible but you can easily walk to Sible, we used to alot..
The secondary school is for all neighbouring villages and has its positives and negatives, personally I never liked it and still dont.
Halstead I wouldnt even look at, it's always had a drug problem, it's full of charity shops, hairdressers, takeaways and the people are not to friendly, I just will not go there atall now, I lived in different parts, the way the person described Alexandra sounds more like Halstead overall...
The mill is a nice place to walk but that's about it