Sugoku Tanoshii or Sugoi Tanoshii?
This morning I was watching the 9 PM news at 8 AM on NHK (we are in Florida and get it via TV Japan on Satellite which means we are watching 13 hours into the future!).
I don’t remember the exact context, but the news reporter was interviewing people after some sort of a festival. One lady said about the event:
However, with one fell corrective swoop NHK blasted the screen with a:
NHK usually summarizes what people say and writes it on the bottom third of the screen. Of course NHK could have simply written it as is considering how short the quote was. But they decided to teach us a mini-grammar lesson.
Essentially, すごい is an -i adjective and the adverb すごく form should be used before other adjectives such as 楽しい. However, you can get around this by using 「すごい」 to emphasize what you are saying or to separate the two adjectives. For example:
Jekai has an excellent entry on すごい. Here is a kind of a conclusion on the great すごい controversy:

In traditional grammar, adjectives are modified by adverbs, so すごく楽(たの)しい “very fun” is correct and すごい楽しい is considered incorrect. However, すごい is also used as an adverb in speech and informal writing, and expressions like すごい楽しい are common and are recognized by some dictionaries.