Pediatric cardiology is a great field, but I would have to say it is the most unlike the other pediatric fellowships, NICU, endocrine, CCM, EM etc. This is because ones lifestyle, practice schedule and compensation vary greatly depending on where you work and what aspect of pedi cards you engage in. That is to say, one can have a largely outpatient lifestyle similar to a regular pediatrician (but seeing most interesting things) is you choice to be in general cardiology vs. a most surgical-like lifestyle if you decide to be an interventionist. In fact, one of the reasons I was so drawn to the field is the variety of practice opportunities one could engage in.
As far as compensation, it really does vary widely with ranges from 90,000 to probably upwards of 400 and 500k. It depends on what you do, how much you work and where you work, big center vs. small, private vs. academic.
The bottom line, is decide first that you like to take care of complex patients over their life-time, are interested in really being the final word on what to do with a patient and working well with many different services: ICU, surgery, echo people, etc...
I would be happy to talk with you more about this.
-V