I think GNOME Shell and Unity are okay. Lemme split my story.
I've wanted to try GNOME shell to see what the fuss was about, especially since Fedora began using it as the default DE. For some reason Fedora hated my internet connection, and seeing how Ubuntu 11.10 was rolling out at the time I wanted to try it, I gave it a whirl in Ubuntu. To be frank, I kinda liked it. The new interface was a little odd, but I didn't really care since I change my preferred layout lord knows how many times. I kinda liked it. I really like how it uses workspaces, and I think it does it the best. It expands all the open windows and you can easily organize windows within different workspaces.
To be honest, though, I'm starting to like Cinnamon better. I just think it combines some of the better features of GNOME 2 and GNOME Shell into one DE. Plus, one of my main gripes about GNOME shell is the lack of fluent customization. While you can customize GNOME Shell fairly well, the tweak tool doesn't organize your extensions. Digging through all of your extensions isn't very fun. Cinnamon puts everything into one convenient menu, and even adds some more stuff like custom animations.
I disliked Unity at first, primarily with Ubuntu 11.04's version of it. It was terribly slow and buggy. Not only that, the boot-up time rivaled that of my Windows 7 partition. The interface seemed like a really neat idea to me. Like a combination of Windows 7 and Mac -- I ain't got problems with that. It was just poorly executed.
Ubuntu 11.10's version of Unity, at least in my opinion, was much much better. Things ran pretty smoothly on my end. It was fairly fast, probably about the same speed as 10.04 on my lappy. What I don't like too much about Unity is the menu. The way they organize the menus and applications in the lenses are abysmal. At least in GNOME shell things were mostly organized in the same manner as GNOME 2 (Accessories, Games, you get the rest). It seems like the Unity menu either uses some other-worldly organization that humans cannot understand or is just bad. My money's on the combination of the two.
I'm currently on Ubuntu 12.04, and it doesn't disappoint. Menu still stinks, but I like the HUD thing. It really helps me find my way through LibreOffice Impress. Been using PowerPoint XP so long that it is really hard for me to find the menu options.
I guess I'm not as mad as some other people since many other DEs do the same thing as GNOME 2 and probably better. For GNOME 2 people, there's XFCE, LXDE, MATE, and the multiple combinations of stand-alone window managers and taskbars. Since last year we've got GNOME Shell, GNOME 3 Classic, Unity, Cinnamon, Pantheon Shell, and soon Zorin Desktop. There's more choices now than ever.
TL;DR Version: I think they're alright, and I don't see why everyone's in a fuss when there's plenty of stable DE choices out there.
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