None for me! I have a 32GB wifi + 4G/LTE through Verizon and I love it! When I purchased it, I knew there were times when I would not be near wifi, so I wanted a cellular model. It has come in handy on many occasions.
I have 64gb Verizon LTE, absolutely no regrets. It's totally worth it to be always connected. Plus LTE is insanely fast and there is no contract so u can turn it off and on whenever.
Depends on if you will need/want the LTE. Works great for me being on the jobsite that doesn't have wifi, and out and about in the city. I use the LTE quite often. Its nice to be able to facetime from anywhere, also.