Love the idea of polymer banknotes - aside from the longer shelf life it would definitely make counterfeiting much more difficult.
That aside, this bill needs to allow for more flexibility as Dereich mentioned. I think there should be a provision that allows the BEP to print and coin other denominations than those listed here at their own discretion. Having the legislature amend the bill every time we want to add a 50¢ coin or $2 bill would just make it cumbersome.
Perhaps we could have the best of both worlds; the BEP is allowed to do runs of other denominations, but these must be limited in duration without legislative approval. I suppose it'd be like the effect of the War Powers Act on presidential ability to wage war. In general, they'd be limited to the denominations in the statute but would have some flexibility for unexpected problems or some anniversary that called for another denomination.