It makes you wonder how we ever 'got by' before waterjet cutting existed. Its such a time saver for aerospace materials (tough and subject to heat affect zone) and other tooling materials. Most people think of the waterjet for thin and thick items, primarily metals/glass/rubber and making a near net 2D part. Cut quality is good, clean and very repeatable. We also see much less relaxation of materials going through this process (compared to plasma).
We have been using it for rough machining large amounts of material from blocks to attain a shape closer to the finished size. How do you do this with a 2D machine, don't you need a 5 axis machine to do 3D parts? We do have a 5 axis machine, but it is whats called a 'Dynamic' unit. Dynamic is a limited 5 axis of motion (X,Y&Z, plus A+B). It helps to offset the kerf angle you would get from the stream. In the Flow machine world, a full 5 axis unit it is called an XD type head.
We have been using various fixtures to orient the part to the head and get the machine to work more like a mill, carving out sections rather than having to mill it all away. This extra operation saves us hours and tons of tooling later on the mill. Would an XD machine do this? Yes it would, but the angle capability of the XD shrinks the capacity of the table. We have a good size table for a Dynamic unit, but with an XD head, safety requires that the travel be limited to keep the jet safely within the tank. You do not want to cut through the side of the tank.