Actually, the Mk.II was quite unique...From a training point of view, they were especially good in the mid-war era, as most aircrew were trained-up on Wellingtons, Stirlings and Halifaxes, which mostly had the same type of engines, making it abit easier.
There are those who felt the Mk.II's were great; - quicker off the deck, good climb to 16-17,000 ft., less exhaust glow, no glycol trouble.....they just didn't quite have the altitude of the Merlins, bombing usually from only 20,000 ft. - Also, they tended to have a swing to starboard on take-off, but that wasn't unmanageable....
All Lancaster variants were awesome....