As with most of Autodesk's apps, the newly released Fusion 360 has somewhat limited appeal. However, anyone who does have use for it will be crazy-excited, and they know who they are. Fusion 360 is the company's collaborative 3D design tool with a more basic feature set and affordable price (free for non-commercial use). The app is not a full-fledged design tool, but it allows remote review of designs.
Fusion 360 exists on mobile and desktop, with all the actual designing taking place on the latter. It supports over 100 file formats like DWG, IAM, IGES, STEP, and STL. The app is free and plugs into your Fusion 360 account so you can view, comment on, and share designs from your phone or tablet. You can even drill down and view individual parts of a complex design.
There's a free 30 day trial of Fusion 360 for all users, but students, teachers, and enthusiasts can get a license for free. It expires every 1-3 years (depending on your use), but you can re-enroll provided you aren't using it commercially. Paid licenses start at $40 per month, much less than the premium AutoCAD software the company makes for enterprise.