Being able to have my GV number show up from my mobile phone when I'm using the cellular network was really nice.
Can you explain this statement? I use Google Voice 100% of the time between AT&T and T-Mobile, and the only number anybody ever sees is my Google Voice number.
The one other Voice-related limitation that I wasn't aware of is that T-Mobile prepaid phones, for whatever reason, can't do conditional call forwarding, which means I can't have the voicemail for calls to my cell number sent to Google Voice.
Yes, this is unfortunate. If you don't care about losing T-Mobile's voicemail service, you can call 611 and they will remove it from your account. So, if someone calls your Google Voice number, there is no chance of T-Mobile's voicemail intercepting the call. However, if someone calls your T-Mobile number, the phone will ring endlessly.