I know that the new Tenere is the XT660Z, but almost everyone is calling it the XTZ660 like the previous one.
I had the exact same question as you last year, I had an Africa Twin, and as I was spending more and more time offroad, I wanted something cheaper that would handle off road better, but still be capable for some decent on road performance. The XTZ660 seemed the thing to go. On the paper everything is there, 168Kg dry weight, 48HP, big tank, Twin headlight (to remember me of my loved AT), low vibration for a single, wind prottection, and cheap so no worries about trashing it. On the net, very little information and as a model considered a non suxcesfull one, the worst of the Tenere.
So I bought one, like new with 22000Km and I have to say that in the real word is all there. I know about offroad one or two thing (own a KTM EXC450 and driving regularry hard enduro tracks once a week), and I have to say that it handles off road pretty good. In comparison to the AT is so much better offroad that is worst onroad. On the opposite of the previous post I find it comfortable and slim in standing possition. I changed and raised the handelbar, because the original one is how to say, strange? On the road is very smooth, and very fast on twisty roads. My have a Givi raised windshield and the wind protection is good. The brakes are not brilliant, but they do the job. The suspension is good for onroad solo driving, too soft for offroad or two up. I stiffend it up. For my stile of riding is perfect. I really don't know why it has a bad reputtation.
If you compare it to the new one, you have 15Kg less and same power. I have previously posted in different forums a question for the owners of the old and new model what is a difference between them, but noone ever answered me. I'm looking forward to test drive the new one, because I really like to see if some decent progress was made between the two models.
So for a suitable relatively cheap explorer bike I recommend it. I will take it in the Tunisian desert next year and I know that it would be more fun that it was with my AT.