Well, not damned by everyone. A landscaper friend spends quite a lot of his time, and therefore derives some of his income, from dealing with the mistaken planting of the same. The point is, he says, that once in place, as a garden hedge for example, you cannot control the side branches as you wish. That is, you cannot, for example, cut them back to the trunk and expect them to grow again. So you get bare bark where you would like some greenery. If you do it early on, you may succeed, but not when the tree is well established. That's his verdict on leylandii.
When a correspondent asked a newspaper gardening expert how to deal with a boundary row of leyland cypresses 15 feet high and 6 ft deep, overshadowing other plants, the answer was blunt: dig the lot out and never plant another leyland cypress, except as temporary screening. Or, he might have added, in a small group in the middle of an open space.
In that case, they look imposing and give good shelter to wildlife. You can, of course top your leylandii if you have them in a hedge, and, if you are very clever, having cut out the lower branches, control the other sideshoots by having them pleached or espaliered but that's the exception.
As a hedging plant, privet isn't popular these days, but it's not a bad choice. Holly is a bit much, but escalonia is lovely. You might even try what was seen this summer in the south of France - a hedge or arbutus unedo. And it was flowering well and bearing the strawberry fruit as the hedge of a roadside house.
If you don't want an evergreen hedge, try dogwood - and you can get more than one variety, brilliant red or yellow stems from November to April; from April to the beginning of autumn, a fine screen of big green leaves, and then, for the last weeks of autumn the most varied colours of the session, leaves going from yellow to apricot to crimson to purple to almost black. The show of the year. In April you cut it back from its six or seven feet to about three and the show starts all over again.