I studied with Verbum for a month before starting my trip round South America.
They were very helpful organising my home stay in Buenos Aires (with a lovely couple I still keep in contact with now).
The school itself is very friendly and relaxed. As well as the lessons they organised excursions to local points of interest out of town which were all worthwhile. Over the month my class size was between 3 and 4 people which I felt was perfect. There was also a good balance between practical vocabulary / situations and the grammatical side with all the many tenses!! My teacher was very competent and also unbelievably kind and patient. Basically, i had a wonderful time and am very glad I started my trip with this course.