Having owned a Toyota Prius for two years now I would consider it one of my worst buys!
If the engine management system says there is a problem (which at minimum is whenever it is cold) Toyota will charge you a standard £50 just to tell you what is wrong... I have previously always had the diagnosis part of a job not charged. Also my special reduced rate worked out at about £100 per hour. Non main dealers do not have the ability to do anything but the basic maintenance which makes the advantages of small tax costs swamped by the extortionate cost of servicing and maintenance.
In most normal cars in cold weather you are able to keep the engine running by pumping the accelerator, but in the hybrid when you start the engine the accelerator does not directly affect the revving of the engine, which means that the engine will stall many times until it decides to rev the engine itself! In-between tries you have to wait for a sequence of 'clicks' (two under the bonnet and one near the steering column) to complete otherwise the engine will not start at all. Because of the size of the batteries there is limited room for things in the boot. Handling is also terrible.
Toyota have also been probably the only make to be able to distibute cars with alloy wheels that corrode and look terrible.
Jeremy Clarkson has also shown that the actual 'green-ness' of the car is minimal due to the environmental impact of the way in which the materials and parts are created and transported.
It does have its good points. £15 per annum road tax and over 50mpg. But I understand that even the Jaguar X Type 2.2 engine gives almost as good mpg but with much increased performance and quality as has the BMW 220d.
If I had my time again I would definitely choose a diesel over a hybrid and will be certiainly be doing so next time.