I read an article regarding Duo 2 on WSJ with the heading "Two Screens, Too Many Problems" but didn't use it personally. That article was written by Joanna Stern. I suggest you to definitely read that article.
Don't have WSJ (I've debated for years whether or not I should pay up, as they tend to be one of the "fairer" news companies), but judging by the headline and the first few lines, they were more concerned about how the software acted than the hardware.
Can't say that'd be too much different from a Duo 1.
I have always said that the Duo is not the phone for the easily frustrated. It suited me almost perfectly as I love using dual monitors in my desktop life, and most of the "bugs" with how it acted seemed to be quirks that once you got used to, you stopped noticing.
However, requiring multiple hardware replacements is a different monster. I don't have anything against refurbished phones in most cases, but after two new and one refurb, I was starting to think it wasn't meant to be.
It seems more people would rather chat about such things in reddit than forums these days, but I deleted my account long ago for personal sanity. That said, I tend to search tech threads there to get a feel for widespread issues. It seems most of the gripes I run into with the 2 are more about software than hardware, and there don't seem to be any major recurring issues yet.
I went ahead and bit the bullet and traded it in at Best Buy. Now I just gotta not drop my Duo 2 until the case comes in. (They were out of stock all over the state!)