I've come across many brands of loops and Magix is the only one I know that are not royalty free. I wasn't really impressed with Magix loops. Back when Acid was under Sonic Foundry then Sony there was some really impressive stuff and you don't see those anymore. I only buy stuff that comes also with midi, presets and one shots. I use to be a sucker during the holidays when ADSR would have 15 packs for $20.
They aren't complete songs but maybe 30 sec. of music. They have their uses for a commercial or a DJ needs filler stuff. They can be frustrating to work with because you can't get them to sound the way you want. I often get them to study. I find the ones that are bloated to 3gb are not always as useful as one that are 700mb.
After NI acquired Loop Loft it seems like they are forgotten. The Loop Loft weekly offer was a big thing in Deals.