I think hanon can be very useful if you use it the right way. There are some exercises that work on important basics, like no 1 (the 3 4 5 4 3 fingering).
What i mean by "use it the right way" is:
try to know your technical weaknesses, then find a suiting exercise (hanon, czerny, brahm, etc) and come up with your own ones in the style of those exercises.
I, for example use one of the hanons (no46) which i modified to work on my trills. And the same one in thirds.
I often play No1 like that: 1 2 3 4 5 4 3 4 5 4 3 4 5 4 3 2 1 (like one of the czernys, but the hanon way

) and if i feel like it, i do more 34543.
The thing with exercises is: use your brain, know what you have to work on.
In fact, i use Hanon as a sheme to create my own exercises.