Microsoft is evolving the Start screen in Windows Phone 8 (and 7.8) to utilize the full width of the screen, support three tile sizes, and offer better customization with all apps supporting all tile sizes and a new selection of color schemes. Here are some screenshots of the new Start screen that's coming with Windows Phone 8.
All screenshots courtesy of Microsoft, via Winsupersite.
To messy for me, I hope there is an option to keep the old layout
Of course the option is there, the new feature is the ability to resize the tiles, so you can keep the WP7.5 with 2 tiles per row style, or you can change them to be 1/4 the size or fill the entire row