If you fly more than 43 segments a year on different airlines, it's well worth it to buy a year's worth. $650 up front passes on a lot of savings down the line. If you only fly AA, then it's even less than that. It would only be like 36 segments to justify the cost IIRC.
I personally use wifi every time it's available. I fly several airlines with Gogo, so it's a no-brainer for me. Will end the year with 72 segments, so that's a net savings of $430.