I've been testing the new Ubuntu 10.4 distribution for a couple of weeks, just to see how much changed since last year.
I have to say that is really good, nice, lightweight, and really easy to use. Is taking the MacOS approach to attract users and I think it will work.
They are taking the right way for PC users, including very useful applications in a single-CD set. But I'm not a normal PC user, I'm a developer, a curious, stupid, bastard that wants to control everything in the system. Ubuntu doesn't let you do that (at least not in an easy way).
I have tried and tried many distributions and still can't find something better than Slackware. Not because it's easy to use(it really is), or because it has huge software sources. Is because its simplicity, is a very simple system, and allows you to change, modify, ruin everything without telling you 'gfy!'.
*Note: Is an old screenshoot, but is still valid.
If you are a developer, and you would like to learn how a Linux system is, or how to use it, you should give it a try.