I was based on the IoM for a few months earlier this year. I flew via the club at Ronaldsway and found Mark very friendly and helpful, as is the Manx tradition.
I inspected Andreas from the ground. There are about half a dozen aircraft based there. The runway is concrete and in a poor state. There are no facilities and overall it has the appearance of decay. Land there at your own risk.
Jurby is near by and is in private ownership and used for bike/motor racing. I believe the runway is available for emergency purposes, and that the intention is to re-open it to aviation and some point in the future.
The island is compact and has many interesting places to explore. Take your NT or EH membership card as that will get you in for free at Manx Heritage sites. People are generally very friendly. Avoid the bike races such as the TT unless you are willing to pay silly money for accommodation, if you can find it. The only downside to the IoM is that the food is appalling!