I'm on Cyta, most expensive option (first bill was 400 Euros with one landline) but in many areas is all that is available. However, can get very good speeds over here. I have a business lite connection (hence the high price) but can comfortably run remote desktop applications across the internet to a server in London. Reliability has also been good, in the 3 months I have been using the service I have not had any downtime.
Providers can never tell you if you can get coverage unless you provide them with a phone number for the property, which can be very frustrating as more often than not you don't have a phone number to give them. Going around to a neighbours house and asking for their phone number might be an option!
If you are abroad and trying to get things set up over here before you arrive, then without help of someone on the ground, then it is virtually impossible. I couldn't get anything set up until I actually got onto the island and could physically walk into an office. Then you have to wait....oh, and if you hold a foreign passport you can expect to be asked for a substantial deposit.