Let's see… Suppose you can use your iPhone for 18 hours on one charge: 5.2% less means 18x60x5.2/100 = 56 minutes less. I bet there are days you would notice!For those who still can remember how to do basic math, (1810-1715)/1810*100%=5.2%
So the battery capacity is reduced by just slightly over 5%. It's unlikely anybody will notice a difference without special measurement instruments, and I bet a typical battery loses more capacity in two years than this.
Maybe other improvements allowed to keep the same autonomy, but I can't help hoping for a much improved battery life… Sometimes I just can't find a power outlet for several days, and I sure wish I could use my iPhone for 3 or more days, even if it means limited calling time and only 2-4 times a day email checks.