I recently saw some screenshots of the new Ubuntu desktop, and deciding to try again after a fair period of time of only using Kubuntu at times and only using Windows as my main OS due to Ubuntu/Kubuntu generally not working correctly with my WiFi card (which I currently lack the money to replace!).
After trying the new version of Ubuntu desktop, I was generally impressed, especially as it now worked with my WiFi card (based on Realtek chipset).
However there are few things that I found really bugged me.
Firstly, and this is by far the biggest issue:
Ubuntu Desktops package management software
It make my computer lag like hell, at points making it unusable! This is unacceptable if you want Ubuntu desktop to grow!
I am not on a bad PC either, 3GB of ram, SATA (Seagate) HDD, with 18gb Ubuntu installation, 512MB ATI graphics card, and a dual core 3ghz processors. It shouldn't be lagging on this setup!
I have now resorted to go into a terminal and using the older apt-get to install my software, as this does not make my system lag, but an inexperienced WOULD NOT DO THIS, they would likely just go back to what they were use to.
I did install Kubuntu on someones older desktop, and found the GUI failed to work on his graphics card, I am not sure of the top of my head which graphics card though I shall try and find out, but it was an older machine. I will file a bug report when if and when I next get enough time on said desktop. Even so, I think Ubuntu could do with been tested on older as well newer hardware!
Menus and toolbars
On the whole I like it, however two things I do dislike, firstly, I have to search for every application, I have not found as I would like an option to look at a certain category of applications such as 'Games' or 'Development' and just see whats there, this is quite irritating I find.
Also, I do find the sidebar a left sidebar a little overloaded and I do feel it do with things been moved into categorys so its a bit less crowded and a bit cleaner.
With the search, I also find the bringing up of affliate product links a bit too blatent, and not generally useful, and although I hardly blame you for encouraging people to buy affliate products, in fact I think it quite a nice way of funding the project, I do think it would be better to do it more subbtle way, and add some other features like showing applications first from repositories (without going to an option at the bottom of the window to search the repositories) and perhaps showing up search results from Google.
Most minor thing, firstly I think the toolbar at the top and window headers are too similar and would look better if there was a bit of contrast between the two.
I also think the topbar perhaps could do with a being bit lighter and perhaps even been semi transparent. Some may disagree, but you're always free to say so here, it doesn't do any harm I think to encourage some discussion on the matter!
Just an added sidenote
In the early days of Ubuntu, and I mean like the EARLY days, I use to use as my SOLE operating system, but I unfortunately had to go back to Windows because a time came when Ubuntu did meet my needs (not wants, needs). I would love to go back to those days.
I think in my parents house I still got a few of the very old CDs hanging about, think they are Warty CDs in fact!!!