Coming from a 920, I've had my 1520 for 5 days and it is, hands down, the best mobile DEVICE, let alone phone, that I have ever owned and used. It is seriously THAT good.
Having said that, it's really sad to see all these users returning their 1520's soon after they've bought.
Keep in mind, the 1520 was the first device to have shipped with it the official GDR3 and Lumia Black firmware - and I can tell you now, that almost all the issues people are having are software.
I had the GDR3 Preview on my 920 and I had a lot of the issues outlined in the "Bugs/Defects Thread" (the touch screen one and apps crashing a lot) - For all those who really like their 1520 but have experienced issues, just wait. the update is coming mid-late Jan, and by the end of January you'll have the perfect Windows Phone.
But seriously - the screen is gorgeous, the camera is fantastic (best camera behind the 1020), its an absolute powerhouse under the hood (I do a lot of mobile gaming and Asphalt 8 and Dungeon Hunter 4 look INCREDIBLE on it), and since I have come to terms with the fact I have stubby fingers, texting is a breeze.
The 1520, for me, kills every other phone currently on the market. That's not my ****** coming out, that's the truth. It is seriously a perfect device (after the software update).