Also found some bugs/features missing from original clock.
Just switched to worldclock on my testing N900 so I can compare both clock apps side by side.

Bug?
If you switch off automatic update and change the time manually, then Save; the application crashes.

Bug?
Even tho I have set the location to London, World Clocks shows Local time as Cardiff.

Missing?
Non-local items in World Clocks cannot be clicked on to show World Clock Details including the map etc.
Also clicking on Local time in World Clocks should resolve to "Adjust Date and Time"

Missing?
The glow around the buttons on clicking is not there.
Useful to provide positive feedback of pressing the screen/button.

Missing?
When setting alarm the original version remembers your last alarm time, worldclocks always shows current time.
(Not a problem for me)

Missing?
When selecting repeat in alarm original version shows full day name 'Wednesday' where as worldclock shows 'Wed' for example.
(Again not a problem, just looks odd when you are used to the original)

Hope this helps.