Plenty of people have thoughts. First, with PADI it's not a course (but with NAUI it is), but rather more like a 'degree' in the sense you complete a number of courses (some required, some elective) to meet the requirements, then pay a fee and get the card.
My comments will deal with the PADI version.
For some, it provides a goal to pursue, and so encourages getting additional training you otherwise might not have gotten around to. For some, having met the requirements and received it provide a sense of accomplishment.
For some, it's a waste of $40 or $50 of whatever they're charging now. Some actively criticize the name on the grounds it labels many divers something they're not ('master' divers), and is some sort of insult to 'real' master divers (e.g.: some Navy divers).
Some will tell you don't waste that money on a card, use it for gear or more dives (note: if $50 is standing between you and whether you can go on a given dive, your finances are tight and maybe you need to spend it on something like, oh, I don't know, maybe your RENT instead?).
The PADI Master Diver certification is a very contentious issue on ScubaBoard.
Now, the Naui version, which is an actual course, well, that's another story...
Richard.
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