Vantaggi
FYI: all of the below is directed especially at prospective teachers. I studied education at university and worked professionally before deciding to travel and work in other countries; Inlingua is one of the schools I've worked for. If you really need money, you can get a job "teaching" your native language there. If you're new to the teaching game, you can get face-to-face with small groups or single students, gain some in-person experience, and try out strategies, activities, resources, etc. (but you can easily do this at any other franchise school too).
Svantaggi
If you consider yourself anything close to a professional teacher, you will most definately be disappointed: this school does not offer or pay for quality education. For reasons that are never overtly stated, they pay little, and they pay (sometimes very) late - do NOT underistimate how much this will affect you. If you work for this school, then you're a freelancer, and if you're a freelancer, you need to be smart when scheduling courses - the nature of this school's customers means you will likely find yourself working very inconvenient hours, which in turn means you may have problems when better opportunities (read: course offers (from other schools)) come along. This last point probably depends on who's managing the school in your location, but based on my own experience, this school has literally no educational program other than handing a series of books to the teacher, and letting him/her teach classes for as long as the students don't complain.