That $25 is your MINIMUM payment. That payment is all that is required to avoid getting hit with the interest from the entire finance period. You do still need to pay it off at the end of the term though.
I bought a new mattress, 0% financing for 18 months. $1500 or so but the required monthly payment was $20 or so. I had Lasik, 0% financing for 12 months, $3500 charge but the minimum payment was $29/month. If you can afford to make larger payments every month, do it or you'll end up with a large lump sum at the end.
As for the high interest charge and being back-billed for ALL the interest if you miss a payment or don't pay it off by the end of the term, this is nothing new. Both of the financing plans I noted above were that way, many are if you read the "fine print".