I bought a Citroen Relay LWB last October and it's been absolutely fantastic. The Citroen Relay, Peugeot Boxer and Fiat Ducato are all exactly the same van and production line, just different badges and the Ducato has some different engine options.
I just had it serviced and MOT'd the other week. It's coming up to 4 years old and despite 85k miles the mechanic said it was all still like new including the brakes, no advisaries.
Long term I can't offer an opinion on reliability, but I wouldn't hesitate to buy another. I converted it into a campervan so I could follow the best snow in the Alps in the ski season and its been flawless. I did tons of research, and it was by far the best value for money, the well regarded Transit engine and unlike the Mercedes/VW/Transit etc its galvanised steel and will have a lot less rust issues long term. The dashboard plastics are cheap, and the rear door requires a hard slam to be recognised as closed, but other than that its fantastic. I've only driven an LWB transit for comparison though.
For a fully serviced van that had done 80k long distance (international) courier miles and impeccably maintained I paid £7,750 and it's top spec with cruise control, dab, touch screen, air con etc. Cruise control is fantastic, though to be fair if you're not doing 16 hour drives like I did its less important.