The ET-2 is a very good tonearm, and a great combination with any of the VPI turntables. I've used an ET-2 on my VPI-19 MkIII for years with great success, and am currently riding a Grado Reference in it. I've found this tonearm to be extremely reliable and very low maintenance. (Being able to adjust VTA while a record is playing is something I will never do without after being able to do so with the ET-2.) As people point out, it needs to be set-up correctly first. Doing so is not quite as difficult as is often alleged, but it can be daunting due to all the possible adjustments. Once properly set-up, the arm has not been the least problematic in my experience, and it stays solidly in adjustment. And the sound is terrific.
All that said, the JMW 12.5 is very likely to be a better sounding tonearm from all I've heard, and so is the 10.5. A friend who had the same VPI/ET-2 set-up as mine recently switched to the JMW 10.5, and he claims the JMW made a tremendous improvement in his system over the ET-2. YMMV.