There is only one small/minor/insignificant problem; our 3 primary carriers (Bell, Telus, and Rogers) have incompatable networks!
This has improved slightly thanks to the recent Vancouver Olympics, but still the lions share of the phones are incompatable.
Rogers: GSM -850MHz & 1900MHz
Telus: CDMA and limited HSPA -800MHz & 1900MHz
Bell: CDMA and limited HSPA -850MHz & 1900MHz
Unless you have an awesome phone that supports 800MHz and 850MHz you are SOL for voice communication and have to buy a new phone if you wanted to hop from one carrier to another.
Another fly in the ointment, even if your phone is capable (i.e. Nokia N900)Bell & Nokia do not operate on 'SIM' cards like the GSM based world+dog do, so you are SOL again.
They should have been mandated to all jump straight to LTE and drop this incompatable bullshit.