I have built and used them on quite often. I usually play 100p maps nowadays, which means there is enough time and space to develop them; wouldn't know about smaller maps. You probably remember that I was against the introduction in province-capturing form, but now they are here, hey lets use them.
Actually the depiction of them isn't very bad, especially the long cooldown after landing. By the scale of the 100p map, it is very rare that you are close to REAL economy centers (core, most likely) of a serious opponent that you couldn't get to without just driving there. Serious wars on these maps are fought on broad and deep fronts (I' m not talking about walking across the noobs here; you don' t need para's for that), and they do have some uses there.
Main uses are the manoever of OTHER troops. When you land para's alongside an amphibious operation, the unload of the seaborne troops goes down by 1.5 hours, which is a LOT; and similarly, when you are moving through big or mountainous provinces, you can negate the "enemy territory" penalty for half a province which can sometimes be really useful. This swings two ways btw, cause the ENEMY is now paying that penalty when moving through the prov for counterattack purposes. It is also nice that you can immediatly start building a frontline airfield for the SECOND part of your advance, which will be be finished so many hours earlier than having to wait for the ground troops to take provs. That's for really deep operations obviously; but in one game, I used that twice (drop para on L2 airbase so it remains operational-fly next para there-drop even deeper-start air base THERE). That gave me the win on that war probably.
As for taking out an enemy airfield, there are other units better suited for that. I actually use strat bombers these days for that, alongside the usual rockets and air harassment.
As for blocking enemy reinforcements, that needs some proper planning. They are extremely vulnerable to air attack, so you either have to give them fighter cover or make sure the enemy has no air force around. Otherwise they are so expensive that you will only want to use them solo, and a stack of a few tanks wipes them quickly as well. So as a blocker, you need to reinforce it with other troops or it is rather useless. But the double-enemy-penalty thing mentioned above DOES make that viable sometimes; I just wonder if you should call them a "blocker" or just an " advance-speeder" then.
Then there's the morale thing... most people consider them "too expensive" which means they are automatically a surprise when they are dropped on an enemy. When you use a few at once and conquering a whole strip of provinces in a matter of minutes, the effect on player's morale can be devastating. As much as you may dislike it, the most economically effective war is the one where your enemy goes inactive as soon as possible; and para's SURE can contribute to that.
After landing and cooling down, they usually have some trouble keeping up with the rest of the army which zwooshed by them; but when they do, they're a REALLY good infantry unit.
So yeah, I ask myself the "shall I go commando or para this game?" early these days; and it can be a pretty tough choice. When I see more sea (NOT oceans!) than mountains in my long-term expansion plans, I tend to pick para's, though that doesn't mean they will be the only units I build in my capital, like I do when I pick commando's.
I'd say their full potential isn't really realized by he player base yet. In fact, I have never had them used AGAINST me except once by a noob I cleaned in less than a day; while my own opeartions with them are usually pretty succesful. Sure they're expensive, but they're worth it, especially now that they come as a surprise exactly BECAUSE they are impopular.
Or are you generally calling us all? Because I do remember there was a forum gang here. 
