Pros
The IH schools differ greatly depending where they ate located and who I running them. Compared to other schools in the EFL industry in Spain they pay you on time and in full, money wise taxwise etc there is nothing to worry about.
Cons
IH Madrid start the year knowing they need to get rid of at least 10 teachers by March as this is when class numbers start to drop. Beware the comments spreadsheet, a tracker that is used by senior teachers to keep tabs on new recruits, it's important to review this on a monthly basis as this is what is used when deciding whether or not to keep a teacher after 6months. Anyone can add to this. Make friends with a senior teacher and get them to add food comments about you. Travelling is a massive part of this job, expect to work 12 hour days with all the running about.