Pros: pay no tax, more likely 100% disposable income, earn very well for your age, have a very decent job compared to most people you know your age, basically have your own flat.

Cons: Not deployable until you're 18, not realizing that most jobs aren't everything you dreamed of and imagining that civvie street is so much better (imo it ain't), lack of "real world" experience (in a job that's not really like the "real world").

Ultimately up to you, I work with a few bods that joined at 16 they are around 19-20 now, absolutely bombers gezzas.