First a disclaimer: Your FAQ editor is completely un-opinionated. Do not argue with him about these topics. Fill each other's email boxes, use the newsgroup, these are INTENDED TO PROMOTE DISCUSSION. However, if you have other topics that you feel belong in this section, let me know.
Some will argue that a good boat does not need a rudder, that they are subject to breakage and you should not learn to use them as a crutch. Often these are the same people who put skegs on their boats because they are difficult to make go straight in certain sea conditions.
Others will argue that a rudder is a tool that improves the safety and convenience of a boat, and not having one is pig-headed and blind to the utility of the device. They do admit, though, that the rudder had better be well constructed and durable.
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A roll is an excellent self-rescue tool, and a good first line of defence to an accidental tip. It does not absolve you from needing to learn other means of self-rescue, because in sea kayaking whatever tipped you over (big waves, high winds, fatigue) is still there when you try to roll, and if it was bad enough to tip you over in the first place, it may make your roll fail as well.
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The Brit boats (exemplified by Frank Goodman's Nordkapp and Derek Hutchinson's Baidarka Explorer) have a certain mystique among sea kayakers. They are designs proven in rough seas and long expeditions, and they have a number of features like built in bilge pumps, waterproof hatches and bulkheads, and recessed deck line fittings that were safety innovations when they were first introduced.
They are tippy, have small hatches and small cockpits, no rudders (see #1 above), and a cadre of devoted paddlers who seem to the unwashed masses to look down on other, lesser boats (gross generalization alert!) Be cautious of being talked into a boat you may not like by an enthusiast who will assure you that this is an 'expert' boat that you will have to 'grow into'. Some are also quite old designs that may not perform as well as some newer boats.
There is a definite character to British-designed boats, born from the personalities that designed and built them, and the seas they were meant to be used on. Choose wisely and well.