I would definitely contact the seller about the
packaging - what if he/she ships this way next
time and it's an expensive cel?  I doubt that
bidder would be as forgiving as you are... =)

If the seller is new to shipping cels, he/she
may appreciate some polite/helpful feedback on
better ways to ship (so the cel will NOT be
damaged).

Regarding feedback... since you received the
cel, and seem pretty forgiving of the condition/
shipping due to the price, I don't think it 
warrants a negative.  I would probably leave a
neutral - something along the lines of
"received the item, nice seller, but poor
packaging".

Anyway... good luck!
Kim