I would buy another iPad, you can never have too many. To anyone considering a tablet, if you don't want to spend 600-1000$, get a Kindle Fire HD. I love my iPad but as far as just browsing, reading, gaming, and what not goes, the Kindle Fire is just as good for 1/3rd the price of the cheapest iPad. iPad is much, much better for school/business, but for the casual user, the KFHD is great.
Also, like Jay and others said, if you've only played this game on a phone, it is a whole other world on a tablet. The size and detail are just amazing. I personally love it because the grid is so much clearer and larger, you can really see every white line and box perfectly.
Edit: forgot to mention, if you own a pc/Mac, and have never playe on a tablet, download Bluestacks. It allows you to play tapped out on your laptop/desktop, and looks even better than a tablet. I highly recommend it, only down side is no finger tapping obviously, takes a little getting used to with a mouse.