It really depends what subject/teacher you get.
I went on a weekday (Thursday) and our lecturer was a full time teacher (as with most TSFX teachers). They tend to be exhausted (after a day of school) and my teacher did make occasional (not rare, but occasional) mistakes.
"Worth it" is quite subjective but for me personally I don't feel TSFX Masterclass benefited me significantly. True, they do go through the theory component and some questions but think about it: If you are a struggling student, how much can 2 hours each week (where little attention is dedicated to your needs as classes have >10 students) actually help you? Very little.
In a typical class, questions are allocated; the teacher does the question, you copy down the answers (with very to no personal attention). Question difficulty, for me, was below my school's exam standards.
Plus, Masterclasses at TSFX costs upwards of $600+ each semester; you can get better tuition centres/private tutors with that money. It just happens that TSFX is the most-advertised. I fell into the trap into thinking that they are "Voted No.1 in Victoria" (as made crystal clear by their gimmicky brochures), but when I enquired for more information through emailing them, they were "voted no.1 in Victoria' by their own selected group of students only.
Tl;dr: There are better places than TSFX out there.