You have to be careful as to the amount of lemon peel you introduce as part of adding the lemon pieces.
Lemon oil can make wine undrinkable, not from the taste - but from stomach upset.
This is particularly the case when peel is added to the secondary where the alcohol helps to extract the oils and for a longer period of time (as the wine is in the secondary for a much longer time).
I would also be careful in the primary as well ... though I'd think it might be a little less prone to problems.
It's been a while since I used a larger quantity of peel in anything, but if memory serves, as an initial rule of thumb the total peel should not exceed about 3/4 of a medium lemon's worth of *peel* per gallon ... that would be very approximately - and even that (in the secondary in any case) might possibly be too much.
I'd certainly run some (gallon) test batches before treating a larger quantity such as 5 gallons ... whether added to the primary or the secondary.
As for flavor - peel does add a strong lemon flavor. It's a careful add though.