Answering the question: Yes, it is.
- Scala is bringing the best combination of functional and OO programming to the masses.
- New languages out there are asked "how do you improve on Scala?", which is a huge change, considering that a few years ago Java was the main comparison target.
- Languages like Java or C# are adopting improvements from Scala, which shows that Scala seems to have done a lot things right.
The explanation of the bad rating on Tiobe is the search string being used by Tiobe:
Tiobe searches for phrases like "$LANG programming", but in Scala (and Haskell) the phrase "programming in $LANG" is much more common. Therefore, both languages suffer from a bad rating. People at Tiobe are aware of it, but it seems as if they don't plan to fix it.
Some other language communities started to modify their websites to cheat the index. For example, the Delphi community went through all their documentation and blog and modified existing texts to read "Delphi programming" and gained a few positions afterwards.
Further info: http://blog.timbunce.org/2009/05/17/tiobe-index-is-being-gam...