I've been testing this release ("Lucid Lynx") on a Dell Precision M4400 laptop. Initial impressions very favourable. It boots quickly, even with full-disk encryption (via the Alternate Install CD): around 30 seconds to the login screen. Much quicker than MS Windows on the same hardware.
Initial setup tasks like setting up MP3 playback, using the WLAN, using the GSM radio, and setting up a Bluetooth mouse (Microsoft Notebook Mouse 5000) were all very simple, and very quick. No messing around with obscure config files.
The desktop looks more polished than previous versions. It's easy on the eye, with a good choice of default colours and fonts really making good use of the hardware.
Only slight oddity is that changing the Ethernet MAC address (e.g. for MAC spoofing attacks) isn't possible using 'ifconfig'. But it's easy with "macchanger-gtk", which is in the Ubuntu repository.
The box itself initially ran a bit warm, and the fan came on a bit. Evidently this is a known issue with the M4400 laptop, due to its ridiculously fast processor. Most of the time I really don't need all that speed, and by adding the CPU Frequency Scaling Monitor to the panel at the top of the screen (right-click, Add to Panel) it's easy to set the CPU frequency to "OnDemand", to keep it running slower and cooler when there's not much going on. By clicking on the icon, you can change the mode as required, so you can nail it down to 800 MHz if that's what you want to do.
UPDATE: Ubuntu 10.04 works happily with VMWare 7.1. I've imported the VMs from my old machine, so this will become my main work machine now. The screen on the Dell M4400 is much easier to read than my old Dell D620: brighter and sharper.