I recently interviewed for a position with this sort of technical interview. I felt it worked very well. The interviewer was able to cover a wide range of topics in varying depth, and could see what I could easily recall and what I struggled with.
With the right set of questions, and some hints when the candidate struggles, you can very effectively gauge a candidate's limits on a subject, and see how they try to puzzle things out when they don't know an answer but know enough to take a good guess.
The key distinguishing factor of this method, IMO, is a candidate cannot memorize enough answers to bluff their way through a good questions list. If a candidate really is an N out of 10 with technology $FOO like they claim, they should have no problem answering most/all of your 50+ N/10-level questions for $FOO (my technical interview consisted of ~2 hours of this sort of interrogation for a straightforward junior web dev position. Interview length, in this interviewing style, is important for ensuring you've exhausted a candidate's book knowledge).
With the right set of questions, and some hints when the candidate struggles, you can very effectively gauge a candidate's limits on a subject, and see how they try to puzzle things out when they don't know an answer but know enough to take a good guess.
The key distinguishing factor of this method, IMO, is a candidate cannot memorize enough answers to bluff their way through a good questions list. If a candidate really is an N out of 10 with technology $FOO like they claim, they should have no problem answering most/all of your 50+ N/10-level questions for $FOO (my technical interview consisted of ~2 hours of this sort of interrogation for a straightforward junior web dev position. Interview length, in this interviewing style, is important for ensuring you've exhausted a candidate's book knowledge).