I like heist flicks, and this is the best I've seen so far. It's got great suspense as the crew of thieves (led by the incomparable Sean Connery) makes intricate plans and patiently prepares for the big day, changing and adapting the plan as needed to cope with unexpected obstacles. There is little in the way of sub-plots; virtually all of the action and plot is part of The Plan. The Victorian setting is great; you start to wonder where Jeremy Brett (as Sherlock Holmes) is, and when he's going to catch these crooks.
I'm a little puzzled by the category of "action/comedy." I'd say this was firmly in the "crime" category, and no other.
9/10