Fedora's ok - I used it at work a couple of years ago and it was solid enough, but not particularly exciting. Currently I run CentOS on my honker workstation, and Ubuntu 9.04 on my laptop. Each has its advantages. I was especially impressed when Ubuntu supported my Sprint Sierra wireless broadband USB modem without any configuration on my part. I just plugged it in, and told it to connect - voila! It did the same thing for my internal bluetooth nic when I installed that recently. The CentOS system is my major development box, and I run multiple guest operating systems in VirtualBox. It has been uber-reliable for me.
So, if you like Ubuntu and are running on a laptop, stay with that. If you want to check out fedora, then run it in a VM until you are convinced that you would prefer that to Ubuntu. They are both state-of-the-art operating systems.