Being relatively new to the linux world I had yet to stray far from the default unity desktop environment. I have been using Ubuntu for a almost half a year now, before that I was an apple sheep for a good 2-3 years. So coming from mac with a dock to unity, felt very natural. However I think unity had several key advantages over mac osx lion for me, the first major one was 2D workspaces through the compiz desktop wall plugin. For those of you about to point out snow leopard had that, yes that is just my point, it was an old OS and I missed that feature when I had it, so the ability to bring it back and use it on a modern OS with great customizability was awesome. Another was just all the other customization and little things here and there that were very pleasing, such as being able to chose if a window always stayed on top, being able to move windows within workspaces from the keyboard and don't get me started on how much I love wobbly windows.

Moving to Gnome

Over the past few weeks I have tried a few new desktop environments, mainly for tests what lightweight alternatives there were. So naturally I tried xfce, which for a lightweight environment, does an awesome job. I also tried kde too see what so many people were talking about, but it felt to windows-like? Now this may suit a lot of people out there, but coming from mac I still see mac as a much better OS than windows both graphically (ignoring windows 8) and performance wise.
I then got to testing out gnome. Now I know, a lot of people, even  have had their complaints about gnome 3.2 (which has gotten better over the recent releases), but I had no background in gnome, and didn't mind installing extensions and I thought it was AMAZINGLinus Torvalds
I'm still not sure weather it was the calender integration to the menu-bar, the awesome overview grid, the plush top panel drop-downs or the general look and feel overall, but I love gnome. There is always however some downsides, and the few small annoyances I have had are compiz keyboard shortcuts playing up and being a pain to fix, chrome has no local menu and doesn't support gnomes global menu so I have lost chrome's menu's. 
Overall however, I think certainly for a laptop environment, Gnome has won me over. The only need I see for unity now is a desktop system and for chrome when I desperately need menu-bars.

UPDATE: I have switched back to unity, I realized that the lack of tight compiz integration in gnome 3 was too much. Unity however has compiz support built it, and I love it too much to let it go. Gnome certainly had some things going for it, such as the very snazzy overview and menu-bar, not to mention the amazing plugins. But when it came to me wanting to make a simple addition such as "when the mouse touches the left edge, launch he overview, because it lacked compiz integration, I was unable to achieve my goal through compiz.