She works from a coffe shop with free WiFi often, so for us it's worth it. She's always been over our on our minute plan, so this will pay for itself, even if it doesn't always work.
I found that I could not dial correctly when her phone was connected to the Telo via Bluetooth, so if you have an adapter, turn off the Bluetooth on you iPhone before trying a test call in your home. Outside of the range of the Bluetooth it should not be an issue, but I have not tested that yet to be sure it's not Bluetooth in general that interfere's with the app's dialer. I can't imagine it would. I think it's more related to the connection between the phone and Telo over Bluetooth.
I believe you can get a refund from Apple on apps that don't work properly by contacting Apple can't you? I'm a Blackberry user myself, so I don't know this first hand. I hope any of this helps in some way. In general I do think the app works sufficiently, but since you have to have the Premier service to use it, it really is overpriced compared with something like Talkatone, which is free for a basic service and a small monthly premium for a premium service. My wife did say the call quality of the Ooma app is much better than Talkatone, but she never tried the premium service from Talkatone, so I don't know if it is that much better than their free service.
Service: Premier 1/30/2012
BELL Canada Port: 1/30/12 - 2/13/12
TekSavvy via BELL FTTN: 25 Mbps/10 Mbps
Setup: Sagemcom 2864 > Cisco E2000 > Time Capsule v1 > Telo
Handsets: Panasonic KX-TG6655S DECT 6.0