Well, he has a point, and you don't have to see it as bad as you do.
I for example, take a look at screenshots before I download anything. And if I see that the software uses a bunch custom controls, doesn't stick to the smallest amount of user interface guidelines, if I see flat instead of standard buttons for example, or if I see an app uses .NET, I don't even download it, making that decisions in just a few seconds.
But, on the other hand: I absolutely like the current image - it reflects Lazarus very well! It has a meaning - actually multiple ones, from standing atop of that other greek IDE to RAD to including the name. All of that is missing in PhilipCopemans suggestions (which are nice, but just don't fit imho).
Regarding the toolbar icons: I like them as well as they are. They're far above the 9x standard, and more important - they are clearer to recognizethan most toy new icons. An option to toogle to 24x24 sized icons would be nice, I have to admit that (just for very high resolutions), but otherwise I think they're more a sign for a good quality beneath than the Delphi IDE, which imho is showing that CodeGear spends too much time on good looks and too few time on quality.
As for the component icons - Delphi showed how bad new icons can be. The newer Delphi component icons are all way more "modern", which only leads to me spending way too much time finding what I need, while the current icons are much easier for locating whatever one is looking for (and yes, I use a horizontal toolbar in Delphi as well, so I can compare directly, not just with that new vertical bar).
The main icon could one improvement though, that's the point where I totally agree
The Cheetah suggestion without a background would probably immediately get my vote, if it wasn't 275 KB just for the icon
and if it would look a bit clearer in 16x16 and 32x32 (resolutions still used most often).
The one thing that lets the IDE look outdated is that it doesn't support docking. That indeed looks very unprofessional (imho), and doesn't reflect too good on Lazarus. But for that, you would have to provide code patches, not graphics
And while the FreePascal internet pages look really nice, this Lazarus portal here looks like a cheap gamers clan forum. I personally don't have any problem with that though.
So, to sum it up: if I had to decide on Lazarus on a quick first look, the current toolbar icons and the splash screen would win over any Vista-style-big-bigger-biggest-artwork.