I get a ton of free stuff at work from my company, and I teach my guys to use these products, but with every car I work on, I use 3M products I bought myself.
They are the most confusing line in the industry, with many products that may seem redundant, or extraneous. But if you are interested, go to their website (which is also confusing) or websites that carry their line of products, "learn the system" and go from there. It will take a while. If you want easy, try Presta. Although I have not used them, they have the most clear line of products in the industry. (Their heavy black pad is used with their heavy black compound, etc. )
But as far as 3M goes, I think the results are worth it. I will qualify my statements by admitting that although I have over 10 lines of product at my disposal, (Ardex, Car Brite, Blue Coral, Eco Lab, Trans Mate, 3M, Edge, Sonus, Optimum, Meguiars, SM Arnold, Schlegel, M&G, etc.) I have by no means tried them all. But I am confident that you will get great results with their product.
I just used their plastic cleaner/polish with fantastic results on the instrument cluster I just removed. I got rid of those "spots" on the plastic much like the type someone else complained about on another post in another thread recently. Their PI-3/3000 compound/Machine Glaze with SMR is a good system to use on all types of cars, especially newer cars or repaints. I haven't disliked any of their stuff,but there are some products I may not use as frequently, like SMR for light cars.
If you wanted to go the K.I.S.S. route, you really won't go wrong with any reputable line of product that you get comfortable with. My advice is to pick one, master it, then go to others if you feel you can do better.
