Charter
Good for learning how to actually fly and make decisions (no standard lesson plans)
Good for learning to deal with commercial pressures.
Good for operating into different aerodromes and marginal weather, can range from departing an international airport and landing on a dirt track.
Generally pretty good for progression onto bigger and more complex machines including twins.
Bad if you want to live in a big city.
Bad for picking up bad habits, under the guise of "that's just the way it's done" or "commercial pressure".
- such as not checking weight & balance/flying overweight/sloppy or non-existent pre-flights etc.