With the name Travelex there are bound to be some fees involved. Some U.S. debit cards have better fee structures for international travel than others so whether the Travelex card's fees end up being cheaper is a personal decision.
The Travelex site lists the fees to get your money or exchange. Since neither the Hungarian Forint nor the Czech Crown are listed currencies on the Travelex card, the amount of your purchase or withdrawal will be converted to one of the listed currencies by Mastercard and then Travelex will charge a 5.5% fee on top of that. There's also a fee of around US$2.50 for any ATM withdrawal.
You must use US Dollars to load the card but it must be converted into another listed currency and an exchange rate applies (this shows up in the detailed terms). Then you'd be charged again to convert purchases in the Forint or the Crown.
Travelex lists several currencies for the card. It's important to note that each individual currency has its own available balance and converting balances among the available currencies incurs a charge of 5.5% of the amount converted. You'd also pay 5.5% to withdraw leftover cash value in dollars at the end of the trip plus a $20 balance refund fee.
A regular debit card tied to your bank account might charge 1 to 3% for a cash withdrawal plus a few dollars per withdrawal. For withdrawals I'd stick to my bank ATM/debit card. For purchases I'd use a Chip&PIN credit card, if you have one. With relatively fewer US tourists in those countries, merchants may be unfamiliar with US-style magnetic stripe credit cards.