I prefer rulers for most of my cutting - I'm actually faster with my June Tailor rulers than I am with the die cutter, and produce almost zero waste.
However, for cutting circles it's great. Also for making raggy quilts - I will NEVER snip one of those by hand again! I was seriously worried about my knuckles and finger joints after my first one, it was really hard on my poor hands. The Accuquilt raggy dies save a massive amount of wear & tear on my hands.
For me it's a tool with a specific and somewhat limited use, but for those specific uses it's the best tool for the job. Maybe when the arthritis really sets into my hands I'll invest in the powered one and be more inclined to cut simpler shapes with it but for now it's my circle-and-raggy-block cutter and that's about it.