From a financial point of view, once you start missing a good number of night matches, the cost of match day tickets versus the season ticket is comparable which means the season ticket is purely a convenience (though it can be passed onto friends, though strictly shouldn't).
The downside of having a season ticket is that you are stuck in the same stand all season. At times I would like to sit in another stand other than the Smethwick (even if it were to cost me a couple of quid more). Season tickets don't allow this. Without a season ticket for the forthcoming season I now have the flexibility of deciding which stand to go in, cos guess what, there are always tickets available, we never sell out.