The web-site
www.visit-spain.co.uk has quite a bit of interesting information on the Balearics and Ibiza. It seems that whilst San Antonio is very lively and frequented by partying youngsters, that other parts of the island are very quiet.
Be careful on property prices everywhere. This recession is likely to get worse and property prices will fall more. The value of the Euro against the pound means that it is now VERY expensive for all UK residents to purchase anything, including property, in the Euro zone. An Euro was worth about 70 pence a year ago. Whilst in Barcelona in November 2008 , it was almost 95 pence on a tourist rate.
Eating out in Barcelona had become much more expensive.
How is the economy of Ibiza faring? I should imagine you will get a lot fewer Brits in 2009.