greeneone12
I was in your situation a year ago - not Persimmon, but another developer which is now part of a group that got 5 stars on that hbf customer satisfaction survey that shabbycaddy posted) . I found negative comments about the developer after reserving as well, so I thought I should respond to this.
The Negative
It wasn't exactly plain sailing. They had a delay, and while we moved at the end of last year, we are still fixing stuff now because the workmanship was... let's say... not the greatest.
I think there are a lot of problems with a lot of developers out there. I'm not sure about Persimmon as shabbycaddy says they're ruthless, but in our case, people actually did want to offer good customer service (i.e. marketing suite, development manager / foreman, etc.). What let us (and them) down was the ability of the actual workmen. Unfortunately, I think it's because workmen in the UK aren't trained well enough these days (and if they are, they end up working for the more prestigious developments like Hide Park One), PLUS maybe they have to do too many things in a short amount of time.
DH and I are professionals who sit in front of PCs most days, and with the help of my retired father-in-law (whose old day job also included sitting in front of a PC, but luckily, he's really into engineering and that stuff), we can actually do the work better than the actual workmen. 
We pointed out a few issues - e.g. paint cracks... which they simply painted over. No sanding over, and getting rid of the debris. The kitchen cabinets, wardrobes and heaters were all wonky (spirit level, hello?). This means that you don't get a great finish - definitely not like that of a show home. I sometimes wonder whether the people who worked on the show home were "special", and not really the ones who built the actual houses.
The Positive
We bought in a nice and unique development, and I like the look of the houses where we live. I like the design of the streets, the mature trees. In fact, there's a lot of greenery around - more than in your average development. It just looks nice. The front lawns/plants are all done for us (residents pay a management company to do that), so there's no annoying neighbour who doesn't mow the lawn or puts a sofa out on the street (which is forbidden) 
. We have great facilities on-site (sporting, playgrounds, greens, etc.) and public transport is near.
Conclusion
Try not to be too fixated on the actual house itself. Yes, the layout, etc. is important... BUT there will always be snags in new builds. And no matter what, you will always end up having to do stuff yourself.
So my suggestions is this:
Make sure you like the area you're buying in, as well as the ACTUAL DEVELOPMENT itself.
Do not buy what you believe to be a nice house in a so-so development, because at the end of the day, the house itself may disappoint. You will find the silver lining when you realise upon locking the house behind you when you go for a walk... that, hey, the area is great.
I can see myself living where I am for a while. Like today, with the sun out and planted flowers blooming around the avenue of trees on the road verge, it actually felt like I was on holiday somewhere else.
That's when I knew that despite everything that has gone wrong... I probably bought the right place.