Of course, looking at history, Rakowski has a very strong point. Back when the first 4-inch devices were coming out, people said it was too big. Then, it happened again with the first 4.3-inch devices, and the first 4.7-inch devices, and the first 5.5-inch devices, and on and on. For the most part, people will complain that a phone is too big, until they use it for a while and get used to the size and the benefits of the bigger display. There's a very good reason why the Galaxy Note has been such a popular phone series, and why Apple thought it had to enter the phablet game.
Admittedly, the 6-inch range does have some limitations that other sizes haven't, namely in how big your pockets are, and if you keep your phone in your pocket or not. I know, I'm a big guy with big pockets, and the Nokia Lumia 1520 (which is just a tad bigger than the Nexus 6) was pushing my pocket limit. So, it is certainly understandable that some may find 6-inches too big.