Apple states the app is compatible with iPod touch. I never tried it. It probably requires you to be connected to wifi at all times to play on the iPod touch.
I connected my iPod touch to my home wifi and i was able to see the map of where my avatar was because of wifi location. I then tethered the iPod touch to the iphone , and I was able to walk around and catch a pikachu. It wasn't accurate, it was very spotty, but I was able to walk around. I just ignored the gps error. I went down like 6 houses down the street. I don't think it would work at a park without wifi hotspots to scan
Wifi requires a internet connection plus scanning the known wifi networks in your area to give you a best guess, and this best guess seems to me to be good enough to catch a pikachu.
Id say its more reliable then the TRACKR!