my sister had an MFI fitted kitchen and it's blody fantastic, only took 18 months to fit....
things from supplying the wrong cupboard doors(wich happened twice), supplying the wrong dinning table, fitting the fridge/freezer door on backwards and a few other things meant the one week job took a lot a lot longer, invovled lots of stress and phone calls to all kinds of advisory services
i would suggest you shop around and ask to view fittted kitchens in peoples houses, there you can ask the relevant questions about the kitchen and it's fitters.