Berkley Nanofil...

Has anyone tried it, seems to be getting very mixed reviews?

I have it on a fixed spool reel that I use for general plastics fishing (I don't use it every trip).
Couldn't complain about it really. You really must pay attention to your knots as it is very slippy. A buddy had it spooled as well and he did not like it. He felt it was inclined to snap anywhere along the length when snagged. I found no such issue. I found that it got a bit "hairy" at the end close to the lure so every now and then I cut a bit off.
I was a bit disappointed at the "price point". If it was a good bit cheaper than braid it probably would sell very well. As it is very close to the price of braid it would not really entice me to change over. So basically...it's good stuff but at the moment it is not enticing me away from my favourite Strikepro Strikewire.

I wrote about it in Irish Angler back in November 2011:

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I tested a couple of spools in Henrys. With the 2 spools I tested I pulled off a 8 foot lenght secured it to the wall and gave it a steady pull. Not a sharp fast gerk. With a steady increasing load I found it snapped along the lenght, never at the knot. I tested the 20lb (9.7kg) spool and was breaking it with ease.... I would guess that it was snapping with about 8 - 10lb of pressure applied. It did this with both spools. That was enough for me. I wont be buying it to test it in real conditions. There are lots of excellent alternatives.