Depends on the device and age of your account. The accounts I have that are the oldest have the most problems which makes me suspect an old building, graphic or unit is crashing out the app before it can reload it's dataset.
Because of this I personally would not update if you have an older device that is not capable of running IOS 8.1.1 and has under 1 or better 2gb of free space. 4.5.1 actually runs faster then 4.5.2 if you are on IOS 7 though you can't get 4.5.1 now.
If you are on IOS 5 DO NOT update to any 4.5.x versions or you will be locked out.
If you are on IOS 6 DO NOT update if you have limited free space and an old account perhaps 2-3 years old as it will lock out. Accounts around 1 year or newer seem to be better in that you can log in but they crash out on raid boss without registering hits.
To those posting that it works, without posting on what device, and OS you are not helping anyone and you could ultimately screw over someone who hasn't updated and is able to log in.