The G11 is by far the best keyboard I have owned to date. As well as looking rather nice, the functionality is also spot-on.
The keys are very smooth and relatively quiet, and the backlighting works perfectly with no bleeding around the edges of the keys. Its not just handy for using the keyboard in the dark either, as it enhances your ability to see the keys regardless of the lighting conditions.
The multimedia keys are relatively standard these days, though it is nice that the volume control is a dial instead of buttons which allows for more precise control. The ability to disable the Windows key is also quite handy for the gamers among us.
The G (macro) keys are also a great addition. Using the included software you can perform almost any function at the press of a single button. Don't be fooled into thinking this is only useful in gaming either, as automated macros can be handy in many other areas too.
It is true that the G11 is a fair bit larger than a standard keyboard, so size may be a consideration for some people. However, I found that it was only 1" larger than my old Logitech 'Internet Navigator' keyboard. So, if you already have a keyboard with a bunch of extra buttons on it, chances are that the G11 wont be much larger.
Of course the G11 doesn't have the LCD screen of the G15, but lets be honest, is that screen really necessary? A nice novelty maybe, but I honestly didn't see any long-term value in it. Losing the screen in favour of a better looking keyboard with more G keys and blue backlighting (as opposed to orange) is a small price to pay, in my opinion.
So if you want a reasonably priced keyboard which looks great and has excellent functionality, consider the G11. You won't be disappointed.