Using Step Up Transformer

I recently moved from a high voltage (240v) country to a low voltage country (120v). I brought along my home stereo system and some other small appliance that requires the input of 240v, to reuse these appliance / tv/ stereo in a low voltage country i bought step up transformer from a local hardware store. HOwever, one thing i am worry about is whether or not there are potential dangers from constantly using a stepup transformer ...hope the expert here can give me some advice