I have already left you a positive review and a 5-Star rating, so I do like your plugin. The things I'm going to bring up here, are a little more about making a good thing, better.
1. Look at the Esponce QR Code Generator. I would like to see you utilize their API, to provide a much more diverse QR Code. I think the Esponce API is far superior to and way more dynamic than Google's API. With Esponce, you could offer some amazing options, with the QR Code, you already display, specifically related to size, transparency and color.
2. There really needs to be some control over the map size, in more than one way. The default map size, for the full-page view, should be a setting on the settings page. The map size, when using the "map-only" shortcode, should be a setting, defined in the shortcode. For instance, I may want my map to be a square, 500px by 500px on the full-page view, but I may only want a 200px by 200px square, if I use it in a sidebar or other widget.
3. Space should not be reserved for information that is left out. For instance, I use all the Contact Information, from "NAME" all the way down to "FAX" but do not use the "ALT PHONE" option. So when this displays on the screen, there is a blank line between "PHONE" and "ALT PHONE" - this looks very odd, from a design aspect.
4. FINALLY ;-) This is both a big deal and probably not such a big deal... depends on how you look at it... I would like to see support for multiple instances of your plugin, all from within the same settings page. I see this being a simple, "ADD LOCATION" button, at the bottom, to add another location, below the default. Each additional location should be accessible, via short code, by adding a 1, 2, 3 & so on, at the end of the shortcode. This would be very nice for businesses with multiple locations.
This is my 2 cents (or 4 cents, as the case may be). I know this is all just one person's opinion of another person's plugin, but I think these 4 suggestions would drastically improve your plugin.