True to its name, Lightning is the fastest browser Ive ever used. Period.
On the other hand, its very minimal. Lightning strives to have just enough basic features to make it lightweight without being unusable; it has support for all flash/shockwave/java plugins, history, tabs, and bookmarks, but dont expect very many bells and whistles. So depending on your feature needs, it can be an advantage or a disadvantage. Best for light browsing for impatient people, like me ^^.
The update is nice, if not very pretty. One annoying thing is that the application is still called Turboweb in the finder, but the name in the menubar when open is Lightning.
Overall, its a fast, stable browser that strikes a good balance between speed and essential features. Great for those "I just want to mapquest this adress and get on with my life already I dont want to have to wait for safaris top sites to load" moments.