A thoughtful episode -- if not especially exciting.
It has the distinction of using flashback to 2004 when Reid was a newcomer and Morgan had a layer of hair. They along with Hotch helped investigate a series of murders only to have the suspect wind up in a coma.
Now the suspect is awake from his coma, the hoped-for trial and conviction is being thwarted by the suspect's amnesia and the effects for 4 years on evidence.
While this plot takes a different branch of the road from the familiar one, you can see that other one all the while. But, there's a reason for that. While this does not have an explicit message, it's provocative.
It does have an excellent Sherlock Holmes-type moment in the middle of the trial. That last's for less than half a minute, tho.