Do we really get unlimited web for 9.95$? Or do they just block you after crossing a set value like 1 Gb?

This is because the subsidized phone will have to purchase the unlimited data + 400 messages plan which is 25$ by itself. So 25-10 = 15$ savings per month

If that is the case we can save about 15$ * 24 = 360$ over a 2 year contract.