From the WMPU editorial:
The Windows 10 for phones and small tablets (or Windows 10 for Phones and Small Tablets)UI has been extremely polarizing. On the one hand, it introduced a brand new design language into the OS. On the other, that new design language brought something that Windows Phone users regard as alien to the platform- the hamburger menu.
The Hamburger menu, for those who do not know, is a set of three lines which indicates a menu. It can be placed anywhere, but in Microsoft Windows apps is usually placed on the top leftmost corner. Microsoft first introduced this to Windows Phone with Cortana, in what many people hoped would be a one-off. The menu was also placed within the reach of the thumb, in the right corner. The next time the hatred sandwich made its return was in the OneDrive app along with a newer design language. This time, rather, than being met with passive resistance, the redesign received a vicious backlash that forced Microsoft to go back to the drawing board. They came up with a better design that mainly pacified users, though it retained the burger menu (I don’t use it btw). In Windows 10 for Phones, Microsoft has shown us that they wish to continue down this path with nearly every app having a hamburger menu as opposed to pivots. But, using the example of the OneDrive app, Microsoft has yet to show us why the menu is necessary....
...Let’s go over what Microsoft uses the hamburger menu now for currently. In OneDrive it is used to hide a few options that could go somewhere else. In Photos it is used to replace the pivot. In people it replaces the pivot. In Calculator it serves as a drawer for all the modes. In other words, the menu is used for whatever they feel like right now.
The article goes on, labouring the point somewhat, but it's a very valid issue to raise. Windows Phone works best when the original panorama/pivot interface is used, with toolbars at the bottom of the screen, where they're easily reached with one hand - having everything sanitised for compatibility with the desktop and/or with Android (or, confusingly, both) would be a nightmare.
Thankfully, it's early days. I've been playing with Windows 10 on the Lumia 630 and only a handful of applications (Calculator and Photos are the two worst offenders) are designed in this way - and there's plenty of time for the pendulum to swing back towards a more traditional Windows Phone style. Come on, Microsoft, don't go and wreck everything you've done so far on the phone... Do the right thing here, please.