Yes, she is. She has a very good balance between zoning and rush down in Highborn, a great jumping kick, an excellent low poke, reliable anti-aerial attacks, etc.
Cetrion and Johnny Cage have slow mid strings in comparison to characters such as Jacqui, Liu Kang, and Noob, yet many competitive players consider Cetrion and Johnny Cage as the two best characters in the game.
Highborn is much better than the other two variations overall, but I understand why Kitana players would want to use Fearless against Sub Zero's slide variations.
Fearless may have better zoning than Highborn in a handful of match ups, but you give up your best offensive as well as anti-zoning options, which is not worth it to me.