My brother-in-law has just got his WO2 at 28, he's been in the army from leaving school. He is very young to have gotten promotions in the way he has and I think a lot of it isn't what you know but who you know. Had some shit postings to and been out to Iraq and Afgan on quite a few occasions even whilst being posted in Germany.
The upside is though that his promotion also came with a 2 year stint in Canada which he starts in July.
The other thing about the Army is the cracking pension you get after serving 12 plus years. It ain't to be sniffed at!!!