Be forewarned, long story... not so short. My first iOS device was a fourth generation iPod Touch, and as much as I liked to use it, one thing that always limited my using it more - or more effectively for me, was the lack of a cellular radio. Reason being is that if I wanted to do anything that required online access I had to search out public wifi hotspots when away from home to go online with it. There were many times I daydreamed of it having a cellular radio - I know, I know the iPod Touch with a cellular radio is called an iPhone ;-) But at the time I wasn't looking for a smartphone or a two year contract per se, I just wanted a music player with a camera, an App Store and access to the internet. I'm also a frequent user of public transportation (busses), so while I was going to or from somewhere on the bus I didn't have any access to wifi or the internet. Now getting back to the cellular iPads - I said all of this to help show what made me make the choice to choose the cellular option when I decided to purchase my first iPad which was the iPad third generation, as well as its eventual replacement the iPad Air 2. Even though the cellular option is the more expensive one, I've found it to also be the more liberating one for me. I can select wether to have a data plan or not from month to month, as well as how much data I want to purchase at a time: from a few hundreds of megabytes per day all the way up to five gigs for a month. Also, I've found another very useful feature being the ability to tether other devices to it. After all one Apple device in my experience invariably leads to the purchase of others...
TL;DR version - thumbs up for the cellular option for the iPad if it's within your means to buy it. You may rarely need to make use of that cellular radio but if and when you do, you'll be thankful that it's there.