My neighbor has this model. At first he thought it was a piece of junk, but has changed his mind since getting the 2008 Navionics Hot Spot SD card for it. The internal antenna is ok, but not the greatest. It tends to loose and acquire its position fairly frequently at least it does when Im running the TM. By frequently, Im talking about once every hour or so. Other than that, its been great with the Navionics chip to show the GPS map detail in high def.