I can hear my OH plug something in, pee and fart on a different floor when all the doors are closed.
The bricks are literally crumbling away, as is the mortar.
The boiler and water cylinder are crap. The immersion is crap.
It gets FAR too hot. 24 degrees at 9am with thick curtains closed when it is 15 outside and quite windy.
Every single piece of hardware without exception needs replacing (3 bathrooms, 3 kitchen sinks).
The windows all need replacing as they rattle like Billy-o. And bits of plastic come off in your hands when you try to open them or even just wash them with a sponge.
Plus many, many more. This is a 12 yo self build new build (we didn’t build it!).
In our old new build flat, however, exactly the same applied to hardware but there were no noise issues nor any of the rest. It was a very solid building. Had to have a wall hacked out due to someone missing a key component that caused damp under one window out of three, but that got fixed. Never heard a peep from a single neighbour (top floor).
That was ten years old when we rented it.
Reasons to be wary: unadopted roads, leasehold scams, clauses saying you cannot make any changes for 5 years, being built on flood plains and causing flooding themselves. Builders going bust and warranties being useless. NHBC warranties are apparently not all that good. Also more and more houses going up around you or other works (ours was a 6 year project for a 10 metre wide tunnel being bored in the field next to us - the OH could not sleep).
It would have to be the best of all builders for me to consider one.