I've seen this point brought up a lot about GDDR5, that it has higher latency.  I'm no tech whizz so what does that mean in a performance sense?  Will games load slower?  Will multitasking be effected?  Just tell me the effects on my experience please.

oh, you mixed things up.
the main benefit is not the latency which is, if anything, LOWER, so faster response time
the main benefit is the bandwith which means you can load more stuff in a shorter amount of time.

latency is thetime from request to start of response.
bandwith is the amount of data you can send per second.

I know what each is roughly.  I thought everyone was saying DDR3 had lower latency but also lower bandwidth?  So GDDR5 is the best of both?

People are too used to harping on about how the latency is an issue because it is in the world of PC's "that's why pc manufacturers don't use GDDR5 for system memory", and that's true, but consoles are a closed system and strict addressing of memory make the latency a non-issue.

Certain fans of a certain console will tell you otherwise of course.