[Elessar]

The ability to upgrade phones is also in there.

The 2 year lock in includes MSRP hardware amortization (at least on my provider), so if you attempt to break the contract, you're paying not only the cost of cancelling the contract, but also the remaining 'cost' of your hardware. That could add up to quite a bit, given that I've seen carriers state that a Galaxy S3 is worth 650. Breaking the contract halfway through its term might result in you paying 300+ for hardware that you actually wanted to get rid of.