The Musar movement has become part of the fanatic religions world which has set itself against the State of Israel as a primary focus. So there is not much in the way of good character one can gain from it today.
Today in terms of gaining good character, it makes more sense to go to Israel and serve in the IDF (Israeli Defense Force) and learn Torah in some Mizrachi [Religious Zionist Yeshiva like Merkaz HaRav], rather than join groups that are have more in common with Mein Kamp rather than true authentic Torah.
[In terms of Torah learning it is hard to say that the super religious have much of an advantage over the Religious Zionist yeshivas. The religious Zionist yeshivas learn pretty much the same material. The difference in learning seems to be evenly distributed. I have met great learners that were part of the Religious Zionist yeshivas.]
One advantage of the Musar movement is that it calls attention to what is really important in Torah--good character מידות טובות and this ironically the very area where the religious fail miserably.