It's not that there is anything wrong, per se, with any of the sheltered accoms that I have experience of.
Always clean, well run, good facilities. The private ones tend to have better accommodation, than the local authority ones. Though I am sure that in some areas this isn't true.
If you get one with a good warden/group of wardens, then you're better off. It does make a big difference.
Living in one can be a bit like being at school/university but without the hope and the future. There is a fair bit of 'cliquey' behaviour going on.
What is interesting is that the age group can be from 60-100 and that is such a broad spectrum of people, so you aren't always with people on your level or your generation. Some of the other tenants will be ill or frail but not ready for a care home. Witnessing this, on a regular basis, so close to home can be very distressing and upsetting. It's almost like watching your future being played out (although not necessarily what happens to you, just the probability of it).
Some people are very happy in their homes, I know of one locally, which is lovely, nice gardens, individual homes, set out in a terrace formation.
Still could not ever face going there, either.
It's such a tough call as I understand the frustration and logistics/costs issues when a relative is struggling in their own home but I honestly believe it is the very best place for them.
I would adjust my living space accordingly, get a care-line installed (don't think this is very expensive) and pay for a carer, if necessary. This isn't always possible, I know, and I think this is a hugely emotive issue that is based entirely on individual circumstance.
All I would say is save as much as you can for retirement, the you have more options. A good care home costs 3-4k per month, sheltered varies greatly but will still cost.