My experience with a scooter was at Stuart Cove's in the Bahamas over 10 years ago during their advertised "DPV Dive".
While there is an option to take a (useless) course, it's not required. I didn't bother. They showed me the controls and went over the basics which took about 10-15 minutes and then we hopped on the boat and proceeded to the dive site where I did one (or maybe it was two) dives exploring the walls and even driving through a couple of narrow openings from reef, out through the wall and back again.
I did a few more DPV dives more recently during a Belize live-aboard trip where there were 2 scooters available to divers at all times. They weren't used all that much, and I can understand why. You see a lot more and I think it's a better "zen" experience without the motorized equipment but they can be a benefit when you've got a lot of ground to cover, say on a large wreck or on a wreck trek or to cover a large reef.
The learning curve is steep, I would guesstimate about 5 minutes from novice to pro.
About the only "take-aways" worth repeating here are the following:
1- watch the battery charge so you don't have to deal with a dead scooter that will need to be either left behind and marked with an SMB to be retrieved later, or towed back to your entry point (obviously not relevant in a "live boat" dive).
2- watch the fast depth changes that are too easy to do, which could blow out your ears.
3- if you plan to buy, keep in mind how long it lasts on a full charge, what sort of a load it can carry, and how fast it will go, among other less important features (dry weight, ease of battery charge and replacement, built in lights, camera, buoyancy controls).
Video below was taken with the Sea-Bob's built in camera. It expires in 2 days according to the website I uploaded it to. Will repost upon request or maybe someone can recommend a free video hosting site that doesn't expire in 2 freaking days.