With new builds everything is under warranty, like Jon said, but doesn't necessarily mean they'll come out and sort it.
Here is a list of the problems we've had with our Barratt home so far:
Moved in 2010, was brand new, no-one had lived here before.
On our third boiler now
Our balcony bars weren't fixed on properly
Bedroom window fell in one day and broke my wrist
Had two sets of bathroom sink taps, one set of kitchen taps, one set of bathroom taps (new sets I mean, on top of the ones that were here when we moved in)
Had new wiring under the sink
Had no water on more than 20 occasions because the pump in our building is faulty. No pump = no water to any of the flats
The pipe underneath the bath (where the water drains away) has been replaced 3 times
A random shard of metal appeared through our hall floor a few weeks after we moved in
The ceiling in every single room has lots of little circle shapes that have cracked the paint off in places (this one is apparently a 'snagging' issue but they don't care)
Our wiring needed work, on more than one occasion, as at one point our electric was tripping off regularly, every 15 minutes, and it was some sort of fault with the building
No lights in our hallway, not even emergency lighting - not good when you're on the top floor
No working plugsockets in the outside hall (numerous times - meaning the cleaner who we pay disgusting amounts for can't hoover)
For six whole months there was a window in the ceiling that was stuck open because the arm broke on it. This was meant to be a safety feature, to help keep the hallways clear of smoke if there was a fire, to allow you to get out safely, and eventually I had to get environmental health involved. During the six month period it snowed, rained and there were storms. The carpets were ruined and they just took another year to replace that.
None of this is caused by the usual movement, for that we've had cracking all the way down the edges of our living room/kitchen (where the tape they've used has blown), and on the rare occasion they have come to fix something like this they've put this weird paint there, to stop staining and further problems, and then they can't even tell us what colour the paint was
And the biggest one...
The ceiling came in! I reported that there was a water mark a few weeks after we moved in, was told they wouldn't come unless it was leaky.
I think I've covered *most* things. Our estate is a shambles. One of the buildings we overlook part of the outside has just crumbled away and I see little bits of dust coming off in the wind. When it is windy I see our neighbours fence panels blow away, guttering coming off and even once I spotted the roof peeling off the building opposite us. They had months of scaffolding up before the repairs were completed.
There are definitely more issues I'm forgetting but these are the big ones.
IF you want to go new build be prepared to definitely not decorate for a minimum of 18-24 months, as that is best to save yourself the stress of constantly re-decorating and be realistic that there will be issues. Some of our smaller issues I've left out are just caused by settling and these are to be expected, however, the above have been a nightmare.
Thankfully a year or so ago our building was finally handed over to our housing association (we rent - praise the Lord hahahahaha) and they've been getting their sh!t together.
Next year we will move to a council house and buy that instead. Then we've just gotta deal with all the problems ourselves