Hit or miss. I was a VIP when I was with them, their service was always great and responses within 24hrs. Others don't have much good to say about them though, so YMMV.
The sites are very affordable and it's a great bang for the buck. Honestly, their sites look awesome and the flash is very smooth and well done. It's hard to find other sites that are DRASTICALLY better in terms of the flash development part. A lot of companies even bite off of them. Having said that, I would recommend you to host your own site as their hosting freaks out a lot of times.
do a simple search on here and that should give you all the info you need. I hate them, others hate them. If you feel lucky then go with them but be prepared to spend a lot of time being pissed off.
Many here have had issues with them when they went through explosive growth. Things seem to have slowed down a lot.
I have bought four sites from them because they are really cheap and quite easy to use.
Like others have said, have them hosted on your own hosting service. I echo this sentiment not wholly due to the competency of their hosting service but because if you host with them you don't really own the site you bought. You have no access to the database, tables, etc.
If you host on your own, you can back-up and manipulate the database tables directly. And if you ever need to move hosting companies (never happens right?) you can backup the whole thing and restore it somewhere else giving you complete portability to the site.
I have had good luck with them. A few issues when I first started up the site, but they did deal with them within 24 hrs or less. So for the price can't complain.