I sometimes forget how impressive things can be with TPRS for the typical students. Let me first share my experiences with learning Spanish as well as teaching Spanish.
In my experience, the Spanish classroom is a place where a few people try to talk and the rest of the people don't really care no matter how hard the teacher tries. The students can learn vocabulary very easily. When it comes to anything else though, they don't get much farther in production than saying things like cavemen. Many do not even try and a majority of the class looks incredibly bored.
In my first 4 years I tried this traditional teaching method. I worked for hours and hours designing lessons and often times would lose sleep trying. My students wouldn't even use the language very much. They were too nervous because they learned the language through vocabulary and conjugating. I gave them all the rules and then let them try to sort out the mess. It wasn't very effective.
Then I found TPRS and discovered that I do not have to kill myself with planning.
So we've been focusing on the structures of the language this year as TPRS suggests. Through circling the information and focusing on the structures and the meaning without worrying about grammar, the students are actually much more comfortable with the language because you start teaching them how it is used from the very beginning.
The other day my students were doing a reading and they were having a hard time with remembering the structure lleva (he/she takes).
This resulted in a beautiful thing the other day. My students had a reading activity and I asked about if a character in the reading takes a boy to her favorite street or to her favorite bathroom. Then I asked who had a favorite bathroom. A student told me that their favorite bathroom belonged to someone in class. From that point on, in Spanish it turned into a discussion on if they would take me to this special bathroom. She also talked about how she played baseball alone in the bathroom and she fished in the toilet. It was incredibly entertaining. I practiced lleva or llevas (you take) multiple times as I asked if she would take different students in the class to the bathroom. Basically she decided to take the whole world to the bathroom except for me! Even my fat cat was invited. The best part... we practiced lleva so many times, it was used naturally by the end of the class.
Not only that, we spoke in Spanish about a bathroom for about half of the class. It turned out that a student in the class taught how to speak 'butterfly' in the bathroom. Another was a dance instructor. This all came out so naturally in the language and was incredibly entertaining.
It helps me to believe in the TPRS method because the students are so ready to converse in the language with you unlike the traditional method.