It can be used on Wifi networks, or on a mobile network.
This is the iPad Air released in late-2013, not the newer iPad Air 2 released in late-2014.
Both versions of the iPad Air are similar (comparison), but the older iPad Air's processor is capable of about half the performance of the newer Air 2.
Regardless, $300 for the Verizon iPad Air is a great value, and normally sells for around $400.
What is the overall value of the iPad Air?
If you are looking to completely replace your computers (laptop and desktop), the iPad Air is a great choice for most people.
It has a long battery life, powerful CPU, is lightweight, and has a relatively large 9.4-inch screen.
However, if you still need to use a laptop and want an iPad to compliment it, check out the more portable iPad Mini.