Way too slow for gigabit internet, not way too slow for what most people actually need.
T-Mobile LTE in one city had an average of 28 Mb/s, enough speed for Netflix 4k, and 95 Mb/s max observed speed. I hate to support cable monopoly arguments in any way, but really for most people 100 Mb/s is overkill.
Of course the cell network couldn't support everybody's internet use with the towers covering such a wide area as today, but wouldn't fiber to the neighborhood and then wireless within it make a lot more sense than running expensive cable to every individual house? It wouldn't be gigabit, but if I could use uncapped tethering (due to smaller tower coverage area) that would be fine with me. T-Mobile LTE is plenty fast enough for anything I use the internet for.