Hi,
Are you looking at a mark 1 vito (up to 53 plate) or a mark 2 (53 plate onwards)? I've owned both (and quite a few other vans as well) so if you want to know anything else about them drop me a line.
I had a mark 1 112 cdi standard panel van and a 111cdi dualiner mark 2. In merc terms the last two digits of the numbers above x 10 are the bhp of the engine. All the vans use the same basic 2.2cdi engine unless you get into mark 2 120cdi versions which get a 3l diesel. The engines tend to be pretty solid with injectors the only common problem and they'll cost about £250 each.
All vitos rust very badly, metallic paints are better than the standard white but still not great. Interior build quality on mark 1's is poor too, lots of bits of plastic coming off, cheap feel etc. Interiors in mark 2 are better but still not where they should be.
I sold my mark 1 after 6 months (i never keep vehicles very long) to get something newer but the mark 2 lasted only 3 months before I got rid as it just wasn't nice to drive/be in. The mark 2's are RWD and have very little grip so the traction control is always flashing even on the low power versions. They are noisy and not very comfy. You also have to be able to cope with the mercedes auto style handbrake on the mark 2 versions.
Have a serious look at trafic/vivaros if you can't afford a t5 transporter (owned one of these too best van i've ever had) as they are nice to drive, fairly reliable (look out for gearbox problems and walk if it doesn't feel right) and good value.
Like i say ask away if you want to know anything else.