I for one have never bothered with "Prime." It's not that hard to combine Amazon orders until they cross the "free" shipping threshold.
Free shipping was great. I don't care about the rest (and cannot play it on my devices anyway. I try to avoid Flash, I don't want non-generic-purpose hardware like a FireTV or something and you cannot access the Prime content from my Kodi/Pi2 in any reasonable fashion).
If you like that offer it might be a great deal. If you pay the full price and only use/get a tiny fraction though...