It depends on what you are after really. Most people who get these are after a particular look in the tank so get the Japanese inspired glass wear to 'complete the look.' You can get them fairly cheaply on ebay, but also spend £100's if you get genuine ADA ones. The intake does little that a normal places intake cant, however the outlet is cupped to circulate the water better and draws oxygen rich surface water into the tank without so much surface water disturbance.
if you have that white scum.. protein buildup on the top of the water surface, the lilly's can be used to get rid of that.. cyclone motion right below the water surface to get rid of that protein buildup.. So no more in tank skimmer...
Depends, If you have the right one for the tank size yes, if not they're little more than a pretty aesthetic choice.
For all my future tanks I want to go for drilled, I love lily's but I like the whole box of water, no visible equipment at all look a whole lot more.