We are coming up on the six month mark on out HP, and can say that compared to our old Mimaki JV3 it replaced, it's a great improvement.
The biggest advantage to us is that it matches our very cyclical workflow. When we are busy, the HP performs very well. Great output, no drying time, works on lots of materials. When we are slow, it sits there quietly and makes 0 demands on our time. No cleanings, no ink wasted, no overflow tanks, no head washings. When work comes in, push the button, load media and start printing. Job finished, push the button and forget it.
Like any new machine, longevity is unknown. Last HP's (5000's)went 9 years with nothing but head and belt changes. Each billed around $1,000,000 of output, so they certainly paid for themselves. Sold them both, and to my knowledge, they are up and running today.