One has to be realitic with the uptime expectations and guarantees. In dedicated hosting, probably most good hosts would be able to offer nearly 100% guarantee in most months. In shared hosting, 99.9% will be very nice, but most of the hosts offer the same and deliver much lower than that.
It is important to know how the host calculate the uptime(only network? less than 30 mts at a time not calculated? any third party monitoring? We dont see any issues here type of arguments?). Also how they compensate for the down time. One shared host told me that they never had an issue with downtime and so doesnt have a policy to compensate
