On one hand this is a slight disappointment for me - apart from not having a phone, I feel that adapting Avatar as a game would work by far the best as a highly immersive single-player experience rather than something MMO or multiplayer-based. After all, at least personally I feel that Avatar itself is by far the most enjoyable when there are no distractions from other people
Aside from that, as a professional game developer I don't hold the mobile gaming market in an especially high regard concerning the actual quality of the games as opposed to using games primarily as a monetization mechanism. Or to put it differently, more often than not mobile games are released for free and all aspects of the game are designed around getting the player to pay as much money as possible through smaller purchases in the game. Compare this to releasing a game with an up-front price, but designing the game itself to simply be really good and worth the initial price tag, and you end up with a far, far better experience - sadly this is very uncommon in mobile games and I very much doubt it'll be the case here.
That being said... at the same time, I never expected an Avatar game anytime soon anyway, so even though I personally will likely avoid this like the plague, it doesn't really feel like a disappointment per se and I'll just keep waiting for something more in tune with my personal expectations