1)Their staff seems not offer full time 24/7 support. On holiday's they are not easy to find.
2)I get outages more than I would like. Generally I would say about every 2 days for about 10 minutes I have no point of comparison though for other hosts
I hosted a site with ASPNix and I had horrible experience. They shut off my site because it was using too much resources without giving me any notice. They wouldn't let me turn on the site to test it after I fixed the problem. They seem to have problem communicating with their customers. Also, I think it is a 1-2 person show without much professionalism.
I asked them for refund and they told me the money was refunded. After 35 days when I still didn't see the credit on credit card, I asked them about it and they said "Oh your credit card was declines ...". Of course they never bothered to tell me ... and later told me to talk to my credit card company. It was just ridiculous ...
In the end I just gave up on ever getting my money back ..