It's not as simple as it sounds. Personally, it's not for me as it's not a regular voice line, it's a VOIP line from one provider and a data plan from another, but if you don't mind putting in the effort, you don't travel out of the country much, it will save you a bundle. An acquaintance of mine, Zecharia, put me onto this--and I thank him for it!
Fido is currently offering a data plan with 3 Gigs of data if you bring your own tablet. It's meant to be used for tablets, but there's no reason why the SIM card couldn't be put in a cell phone. Only thing is, you need to bring your own phone into the plan and know you won't have a traditional cell phone line.
You will get your cell phone line from a Fongo.com, VOIP provider. They will charge $10 for 6 months of unlimited texts, so $20 a year. Other than that, porting your number over will cost you a small fee.
The reason you may want to pay for this is many don't have wifi/data text apps such as WhatsApp, and you may need to be available to receive regular text messages.
Total cost is $15 a month for Fido, $20 a year for text messages= yearly cost of $200!
If you travel to the States, you'll want to get a different provider as the SIM card from Fido won't give you data in the States. Roam Mobility offers SIM cards for around $10, and with it, you can get data only for $9.95 for 3 days, or a regular phone line with text and data if you wish as well, starting at around $5 a day.