Well the Xsara Picasso is great value if nothing else. I know for a fact you can haggle the dealer down to £8,000 for a new 1.6 LX because Citroen have 2 (Yes Two) new Mini-MPV's coming out. Both based on the Citroen C4 one is a five seat, high roof estate style car (Similar to Picasso) and the the other a seven seat, mid sized mpv. These will arrive in the UK next summer hopefully. This leaves the Picasso with a sore taste in its mouth as trying to sell one of these second-hand will not be hard but it will not be worth alot (I have known a 2001 model change hands for as little as £1250 in good condition, low mileage and high spec).
My In-Laws Own a Citroen Xsara Picasso so this is how I know about them, They have theres through the motability scheme, and have a 1.8i Desire. Its pretty roomy inside, although the dash takes a bit of getting used to, and the interior feels drab and grey. I like the Visability of the car, but lack of sunroof is disappointing. Also another point i'd like to make is excessive tyre wear. They go through a set of tyres faster than my Renault Megane Scenic, They check the pressures, weekly, drive very carefully to conserve fuel, but still replace tyres every 7,500 miles. I replace mine every 13,000 miles if not more!
Anyway. If you are looking for Investment, specification, and dealers who actually care, Look around. May I recommend for Investment, a Mercedes B Class, Mazda 5, VW Touran or Honda FR-V. Specification, A Vaxhall Zafira, Renault Megane Scenic or Ford Focus C-Max. And Good Dealers, Kia Carens, Hyundai Matrix, Ford Focus C-Max, or Renault Megane Scenic.
Pricewise Alternative's to consider for you are Kia Carens, Hyundai Matrix, Chevrolet Tacuma, Fiat Multipla (Got rid of the stupid design, now respectable) Or Seat Altea (Highly Recommended if a little smaller than all its rivals)
Good luck my freind in purchasing your car regardless of what you decide.