I bought this backpack for my mobile recording rig, but I ended up finding many other uses for it. This comfortably fits my laptop, interface (focusrite 2i4), midi controller (Akai MPK mini mkII), cables, mics, sustain pedal, and a mouse and numpad. Granted, it was stuffed to the brim, but the point is that everything that was necessary fit inside without feeling like i was going to crush anything.
The main pocket is the best. The padding is more than sufficient and the size makes it perfect for a business backpack too. Laptops, books, and papers fit perfectly and snugly (so not much risk of unwanted folds or wrinkles).
I also use this as a gig/instrument repair bag. I drum in my current band, but I'm also responsible for bringing extra equipment for emergencies or repairs (tools, cables, strings+winders, extra mics, picks, drum felts,). This bag makes it super easy to keep everything well organized and separated by function.
My only complaint is that it tends to stick out backwards quite a bit and I've accidentally hit a few people with it. It's not the most form-fitting backpack I've had, but it's meant to protect the contents.
Awesome little backpack.