In terms of Kabalah I  was pretty impressed with the Kabbalah Institute for a few reasons.
The first is that the only edition of the Eitz Chaim that I understood at all is the edition of the Kabalah Institute. Also when I was in Tzefat {Safed} [In Meor Chaim the kirya of Rav Ernster]  I use to see them by R. Pinchas Ben Yair once every month when they came up from Tel Aviv. They seemed to be a very nice and wholesome group.
They do not have a good reputation in the religious world but as far as I can tell that is in itself one of their best points.The religious I think are jealous of people that have authentic spirituality.

My own experience  was to learn the Ari outside of the yeshiva schedule. I was part of the yeshiva Mir in NY at the time so I was doing Gemara during the regular hours. On the side I learned the Eitz Chaim. But when I got to Israel I did very little kabalah (if at all). Still I think the little I did of the Ari was helpful.[I am sad to say I did very little learning Torah in those days. If I could rewind the tape I would have learned in the kollel of Rav Ernster of gone up to the Litvak Kollel of Rav Fivelson and sat and learned Torah.
The Ari is a good explanation of Torah, but learning the Ari does not take the place of Gemara, Rashi, and Tosphot.
[The Ari has the problem of all systems--it is liable to abuse. People however will always find a way to abuse any system. Abusus non tolit usum.]

The kabalah as developed later than the Ari is only from the Realm of Holiness from these basic people, Yaakov Abuchatzaira, Rav Shalom Sharabi,  the Ramchal and the Gra. The rest of it is sadly all from the Sitra Achra and very damaging to an astounding degree. The grandson of the Reshash wrote  a very nice sidur base on the Reshash but I think it is only sold in Mea Shearim. At least that was the only place it was available  few years ago.

The advantage of the Ari is that he gives a nice understanding of the Torah. The disadvantage is he is more liable to abuse than almost any other system-to the degree that is amazing. Still without him, I see no way to understand the Torah.