Differences between Arduino Uno SMD and Uno DIP
As far as I know there is no real difference, at least not directly related to the SMD.

There are many clones which sometimes have slightly different behavior or protection.

But for the SMD the only disadvantage is it cannot (easily) be replaced.

I have one original one (with DIP) and several clones and so far I did not found any difference, except for having mini USB instead of normal USB.