It's a popular topic on these boards; this is a
reasonable example of a thread. Post 9 makes a good case for using the point + power technique in all aircraft. Do a search for 'Point and Power' to uncover lots more heated debate.
It helps me to think of it like this:
You want to fly your airliner down a constant descent path. You have a ready indication of this in the cockpit - the ILS glideslope - and because of the inertia of your large aircraft, once you have got it descending at 3 degrees, you want to keep it there rather, than chase it all the way. Therefore slight deviations from the glideslope are immediately dealt with using pitch (using power would result in a delay for spool-up or -down, and hence larger divergences from the glideslope). Because you used pitch to correct, you will now get a change in airspeed. You correct this change in airspeed with power. Due to lag in this cycle, the airspeed may wander above and below the target speed by a few knots. However, because airliners fly their approaches with a higher margin above the stall than is the case for light aircraft and gliders, this variation in airspeed is acceptable.
Of course the expert answer is "pitch AND power control speed AND descent angle". However since we are all mortal I offer the following sketch to show the practical differences between the 2 techniques. Deciding whether it is more important to fly a constant approach angle or a constant speed should help you decide which technique is more appropriate:
If you browse through the thread I linked at the top, you'll see mention of the US Navy. They are unusual jet operators in that they don't practice 'point and power'. The reason for this is that when landing on carriers the aircraft must be at exactly the right airspeed, with
exactly the right AoA on touchdown or the arrester hook will miss the wires. Because of the need for total precision in AoA, it is directly controlled with pitch. Therefore they must control approach angle with power. They're assisted in doing this by the 'meatball', which is effectively an extraordinarily sensitive PAPI. They do have four wires to choose from, but it's pretty impressive nevertheless!