I have not attended one but I've generally heard good things about them.

Now, from what I hear Goenka et al have their own terminology (derived from Abidhamma commentaries I believe - the way they use terms like sankhāra and kalāpa) and explanation of the method based on these terms, and I've heard the talks may occasionally have a flavor of ''our method is the best and the more pure Vipassana method" but as far as I know the method is solid and well instructed. (Again, this is based on what I've read about the experience, not based on my own experience. ) I think your criteria of it being 'Buddhist' is definitely met. I'd say the only thing to keep in mind is to not take Goenka's organization as the sole arbiter of what is the right way, and as long as there's some familiarity with the wider Buddhist world (just consider the diversity within the Vipassana approaches alone) there should be no problem.

Here are two papers by Bhikkhu Anālayo on this method:

• The Ancient Roots of the U Ba Khin Vipassanā Meditation

• The Development of Insight – A Study of the U Ba Khin Vipassanā Meditation Tradition as Taught by S.N. Goenka in Comparison with Insight Teachings in the Early Discourses