For the forth time and thought I would try a GPS for the first time.
What do you want to use the GPS for? Is it for navigation or recording your trip? Is it to navigate to a destination, or browse for routes to follow?
Navigation on a GPS device is good when you are following a track. You can either define a track before your trip (which does not seem what you want to do) or give a destination for the unit to calculate a track to reach it.
Browsing for roads, points of interest, & destinations on a GPS device with small screen & low resolution is cumbersome at best. It will appear even more so after using an iPad with large screen, vivid colors, & fast response to finger gestures.
Depending on how you want to use the GPS, consider investing into an external battery
for the iPad with an app
that stores maps for offline use when not connected to the internet.