Very heavy, small fuel tank, when they work they are good but they have awful reliability problems. If you do get one look out for the ones with roarer burners fitted as they work better. When the MOD modified the burners they dropped a real bollo*k. To be honest I've kept one just as a collectors piece but I'd not think of taking it away with me on camp.
The new army No12's are fantastic, burn paraffin and diesel (one of the few stoves that does burn diesel fine) but they fetch big money, as Widu says the Optimus 111 does a better job, is smaller in pack size, ultra reliable and affordable (budget £40-£70). The 111 roarer burner is a paraffin stove only while the 111T will burn paraffin,Coleman and meths. PM me if I can help further.