$25 for the 2gig/mo data plan is all the extra it will cost me. If I thought I could hold it at 200mb/mo, it would only be $15.
You already have unlimited texting? That data racks up fast too. You can monitor it online though to watch what you're using.
I don't have data or texting, mine would go up around $55 with tax. I just can't justify an extra $700 a year or so in expenses right now. I am one that uses my computer for more than just email and surfing.
The only advantage to me would be not having to have my laptop when in front of the TV, or being able to have internet access the two hours a day or so I'm not in front of a computer.