I use a little helper program called Synapse on Gnu/Linux/Debian/Xfce, and before that Alt+F2 (though this is a little crude.).  I'm running Windows 8 as well.  And I have Gnome 3 on my laptop, that I log into occasionally.  I try Ubuntu every now and then to see if Unity has been polished up a bit.

I don't like the Windows 8 launcher.   I should replace it, whereas I didn't mind it in the start  menu.  I'm used to using it like that.   Before that, the Run dialogue sufficed (but again that's pretty crude). In Windows 8 I find switching interfaces really jarring, I hate it.

Synapse pops up a window in the middle of the screen, that I find less intrusive.   It's pretty clever,  Some things are a little odd though.  I type 'Fil' for my file manager - but typing 'nautilus' does not work.  Whereas I type web, or epi (for epiphany) for the browser.  It favours previously selected apps, which is pretty good, like the recently used apps in the start menu.  I think that's similar in Gnome 3 too.

It's a bit of a hidden feature that you can just type.  Make sure you tell Ubuntu users that, if they haven't discovered it.  I find the oversized icons and right hand side menus really weird and difficult compared with a succinct menu.  I like my Xfce Debian menu, that divides the menu up into vague categories: office, internet, multimedia.  That compliments Synapse pretty well.

As you say, to use the launchers you need to already know what you have, and the name of them.  I like the idea of typing something generic and then narrowing your focus.  When searching in Windows 8, you end up with three areas to search, which doesn't feel quite right.  Well it doesn't with the keyboard at least.   I'm finding the UI very clumsy.   I can get by with it though, just like I can get by with Unity.  Though currently I prefer Xfce.

I remember reading about Gnome 3 early on, and it was purported to do some very clever stuff.  Much of the Zeitgeist/launcher features embedded into the desktop, but a lot of that seemed to get lost.

The last time I looked at OSX there was Quicksilver as an add on.

One problem seems to be the indexing needed to get those tools to work.  Seems fine on my Debian box, but Ubuntu 12.10, seems to always be running some background indexer, that bring it to its knees.  I should also mention the issue of privacy.

Likewise @dreymar,  I never thought I was a huge fan of menus.  Until they were missing.  The large icon interface just doesn't add anything for me on a Desktop OS.

Menus can give you a very succinct and fast overview of what's available on your system.  Deeply nested menus though aren't so good - you know like the old Accessories menu in Windows.   These and small target areas can be difficult and fiddly to select with a pointer.

It's not immediately obvious to me which applications are installed under Ubuntu/Unity, Windows 8 and Gnome 3.  If you already know what you're looking for it is not so much a problem.

I was trying to launch a program under Ubuntu/Unity and jumped through loads of hoops.  I ended up trying to install the application by using the software manager only to find that it was already installed. 

There's quite a lot of mystery meat navigation going on with these new interfaces.  Some require some magical (and non obvious) gestures.  It's bad usability.

As a proficient typist I don't mind launching apps by entering text.  But I'm sure it's a bind for others.   A little guidance can help such as filters and auto-suggest.  Having said that I'm terribly confused with Unity's Lenses, and I don't know if it's possible to list the traditional application menus alongside it's HUD.

(Type 'how do i use w' into bing, and the first suggestion is 'how do i use Windows 8,' which suggests many people are struggling.  I got my hands finally on a tablet running the OS - and I watched five out of five people totally fail to operate it.  I struggled, and I already run Windows 8 on the desktop.)

> I don't use Mac, but by pressing Apple+Space you supposedly bring up Spotlight for a similar functionality.

That shortcut is the same as the default for switching the keyboard layout in OSX.  The same shortcut is now available in Windows 8.  You might want to remap Spotlight's shortcut.

@vaskozl,  I guess that Microsoft want to take a cut in app sales (they want a piece of the Apple pie).  Taking apps out of the browser, and having them coded to their platform - helps them monetise on this - and keeps users confined to their walled garden.

It also has one major disadvantage: They are effectively trying to block every single operating system that doesn't come out of Microsoft's headquarters.  The same kind of stuff that get them in trouble with antitrust law by abusing their monopoly in the 1990s.  As if "Secure Boot" being forced on ARM machines with no way to turn it off wasn't bad enough.

The Web is universal, not run or owned by any single company, and can be accessed by any computer with an Internet connection and a web browser.  Windows/Metro "apps" are not.  You need to pay Microsoft (again...).  I'll take real web sites over "apps" any day.  And that's any "apps"--iOS, Android and Metro.