If you go with the Eggfinder GPS, I suggest throughly reading the user manual. Cris tends to go on a bit (just my opinion), but on the other hand, there's some important info in his instructions which many times are missed. Like changing the frequency, the sequence for turning the equipment on, adjusting the display, antenna info, using the Eggfinder with geographic applications, battery requirements...
I don't think any rocketry-type GPS is currently plug and play. You must get through all the operator type errors with experience before you will absolutely need it to find your rocket.
If you get a Featherweight GPS it's a bit more intuitive in my opinion, although there seems to be frequent required updates. It's settled down a bit since the first release, but I suggest checking for updates the day before the launch. Btw, cellular service is not required to run the Featherweight. So, people have obtained old iPhones/iPads with just WiFi to run the application at the launch. This is what I do for 2 stage flights. I'm running two Featherweights on my iPhone and iPad for the booster and sustainer and choose two different voices to announce their status.