You must be going for the lowest-end model, because the middle-tier iPad Air had 32GB while the new one has 64GB for the same price.
Among the other reasons why the iPad Air 2 is worth way more than $50, even if the Air 1 has more storage:
1. Twice as much RAM in the new one
2. A8 processor and associated graphics system = waaaay better (specifically, 40 percent faster CPU and 2.5x faster GPU)
3. TOUCH ID. This is in ALL CAPS because that's how way awesome it is. So secure, so handy, so Apple Pay
4. 8MP camera instead of 5MP camera, other internal camera improvements
5. The Air 2 is 18 percent thinner and 32g lighter than the Air 1, despite being a lot more powerful. Much easier to hold
6. Now available in gold if you want (not very important to me, VERY important to some people)
7. 802.11ac and MIMO support, in short better connectivity
8. More compatibility with LTE/3G standards in other countries (important if you travel)
9. Reduced-glare coating on the new iPad Air 2
Don't get me wrong, if storage is your top priority then the original iPad Air should do you just fine. But IMO the iPad Air 2 brought more than $50 worth of improvements.