Overall, I really do like Reanimated treasure ninjas, but they are indeed hard to find a place for them.
Now, the fact they are 2 stars is both a disadvantage and advantage at the same time, depending on how dedicated to pulling you are. If you are satisfied with just 3 star ninjas, it is far easier to obtain 3 star Kage treasure ninja, and most of them are very good. On the other hand it is much easier to get 4 star Reanimated ninja than it is to get a 4 star kage ninja.
(Non rare pulls however are a nightmare though, as they only yield 10 fragments per pull)
But the ninjas in there are very gimmicky, which means they are all fun to play, but also very situational.
Rasa and Gengetsu (super rares) are nice, but unusable outside of arena because of their stars.
On the other hand you may get these guys to 3 stars in half the scrolls required to get kage super rare... I still wouldn't recommend going for them.
Mu would be my pick for the best ninja in this treasure, and I really can imagine his 4 star version do some real work. It';s a good ninja no matter what way you look at him.
Kinkaku is also nice due to the fact he shields and buffs all reanimated ninjas. But just as Bee, this skill of his is not that relevant yet, they will both become far more important when reanimated jinjuriki arrive.
Kabuto and Ginkaku are both a bit underwhelming. They do have their use on rare occasions, but meh.
Non rare ninjas are good, GNW hinata and Temari especially. But these guys are dragged down by being 2 star, and only getting 10 fragments on pull.
So yeah, overall this treasure is not as good as kage treasure, but is much easier to use. I myself do want to get Mu higher, but with next treasure coming up, it's not really the best thing to do, especially since it will change the meta game a bit.
That being said IF you like the ninjas in there, have some good strategies for them, or just enjoy their gimmicks - feel free to go for them. It doesn't really matter that much what ninjas you use in this game as far as you like your team. Of course you will not beat some players with a bad team, but truth be told, you definitely won't beat them by using their team either :P