After being sick for a couple of day and in pain, I decided to try and install Mac OS X Leopard on my trusty Macbook Pro and see how it fairs.  Since I had a lot of programs and data on my computer I did a backup and then proceeded to upgrade the system instead of a fresh install.  Havoc was awaiting me in the distance.  Mail failed miserably because I was using the httpmail plug in to get my hotmail account content on the computer.  Firefox was acting weird also.  Other applications refused to run or were simply acting weird.  Nothing changed in terms of looks except the menu bar on top.  It became more transparent and the Apple logo was a varying shade of gray.  The preferences change a bit but nothing noticeable.  After a couple of day of suffering and realizing that I wasn’t getting any work done because of applications freaking out on me, I decided to erase everything and start from scratch.  Of course, I backed up my user directory and proceeded to erase and install, fresh install.  That did wonders.  the wall paper changed to the green Leopard drop and things were looking better.  I setup Mail and things went flawlessly but the httpmail plug in did not work.  Firefox was a bit better but still gave me a headache.  What was surprising was all the apps were a lot faster when you start them up.  Skype was displaying its startup screen with the image all distorted and AdiumX worked like a champ.  safari is blazing fast from star to finish.  network drives were visible and brows-able a lot better then before, especially windows shared drives.   Wireless networking is better and a lot more stable when connecting to random access points or when moving from one place to another.  What can i say, i love leopard!  The preference pain for the networking and the sharing has seen some changes.  it is organized in a better way and simplifies configuration.  It also helps you and shows you what you need to do to see windows machines in the network panel in finder.  It also automatically connects as guest to windows shared folders without the hassle of having to mount each one you want.  Spaces is nice, but compared to VirtueDesktop it is lacking in features.  It is not graphically pleasing when it does its transitions but it is better suited then VirtueDesktop.  For some reason the help system is not working, or it works but there is nothing to be displayed.  Terminal finally got tabs and you can open many many terminal sessions with tabs.  It also has preset configurations to simulate sessions that is a lot easier to use and understand.  Sorry no tabs in finder yet and there seems to be no way to simply change the looks of OS X.  The Menu bad suggest and easy skinning option but I didn’t find anything that would change its looks. 
Preview has been revamped.  It is better, faster, and handles files accordingly.  PDF files look better in Preview then before.  The drawer shows the indexes and navigation is better too.  The overall look of Preview is different and better.
The cover view feature in Finder is, to me, eye candy.  I don’t get it, honestly, and it is quite useless.  It would, however, really shine if my future Mac came with a touch screen and understood gestures.
Overall, leopard seems quite responsive and fast.  It feels like its taking advantage of the new Core 2 Duo processors especially.  The interface is a lot more shiny and feels more bright and polished not dull and off which makes it look very different when you first start Leopard. 

Take a look at ThinkSecret’s Image Gallery of Leopard