Azure, rusty, and other super dragons: do they live up to the hype?

I used to use them, but there was a situation where I would win anyway. What can be said about them? They are good tanks; you can use one or two of them to absorb damage from a strong enemy stack without worrying about anyone in your army dying. And they have good speed, which gives an additional advantage. But I wouldn't use them instead of level 7 units; instead of archers, yes, they are a great replacement. Level 5-6... It depends on the specific creatures; instead of cyclops or manticores, yes; instead of nagas or ifrits, probably not. Instead of level 5 units, probably yes.