This kind of welding is called oxyacetylene welding. It can also be done with MAPP gas. Oxyacetylene is a good clean steel and cast iron, but it usually doesn't work well with nonferrous metals. Oxyacetylene welding may be tricky, but it does provide good weld, especially for mild steel and cast iron. High alloy steel with high carbon content and the addition of alloying agent have high porosity. It is most similar in the process of TIG or GTAW welding, which is considered to be a difficult welding form. The strength of the weld is generally considered to be with the conductor, or MIG welding. If you are looking for ease of operation, I would recommend MIG or Stick(SMAW) welding, because welding quality is good for most people and has greater flexibility for welding alloys. If you plan to weld a lot of high-precision things, or mostly nonferrous metals, TIG will be a great way to learn.
