Apple (with their Mac interface) is not the most innovative on GUIs designs. It always coppies features available on other systems:
-For example, The dock is based on Next dock, and it is releasod on OSX due to high demand by users for a taskbar (like in Windows).
That it makes great OSX (and earlier Mac OS versions) is the usability, the well implemented GUI functions, and the consistency between aplications. Of course, it make always well and beauty designed designs. This is true! >

But Apple have great problems for mass acceptation:
-Their hardware are very expensive (if you not purchase a monitor-supplied computer, you need to pay a 2000$ computer!). Yes, they are very beauty, but most of the users have a monitor.
-There's not a lot of programs for Mac

. And the programs you find in other platforms (such xmms, Sonique, etc.) are shareware, you need to pay for them! BTW, when there's a sufficient set of programs for Mac, Apple changes the computer architecture (from 68k to PowerPC, from Mac Binary to Carbon, from Carbon to Unix-Cocoa), that means a reprogramation of all software available. This is not good.
-The Apple support: Apple computers are hardware-clossed (in theory), and you need to get support from Apple or affiliates. 3 months after purchase, you loses the support, and you need to pay for support (not if you are friend of a supplier). This is not a drama, because the Macs are normal PC's (overprized) with a motherboard, a CPU and a graphic card specially made for Apple operative Systems; all other components are the same for windows: ide, scsii, usb, cdr, you can also try to install a PC radeon and install the drivers! But a normal user don't knows this, and some PC vendors always says: 'sorry i completely unknow the Macs'. Macs are expensive if you have problems too

(in opinion of most users).
-A part the contrary propaganda of lots of PC vendors to Apple products.
And the last and very TRUE:
-Mac users are very prepotent, specially to Windoze users.
I'm a Windows & Mac user, actually with booth platforms on my desktop. I said windows shadows and animations using WindowFX prior to the first Aqua screenshot, and DesktopX have more featuresd than Aqua interface, but i repeat:
That it makes great OSX (and earlier Mac OS versions) is the usability and the consistency
If some Mac user says:
'Apple always invent GUIS features'
don't listen to it, and say:
'Please, do you know cumputers GUI history?'
'Do you know Xerox?' - 'And GEM?' - 'And Amiga's?'
'And NeXT?'
'ANd the horrendous taskbar at bootom of Windoze screens?'
I listen always you opinions here, on Internet, and any day i listen the opinion of this kind of Mac users, and i always says to them the Tips and the Secrets of Mac OS and their programs.
Your computer is not better than other that costs the half you spended, and two times faster.