1) Starlink usurps nation-state controls, period. Whether it is enabling service when the local government doesn't want it, or denying service to an ally the US is trying to assist. My hunch is that if Elon keeps pushing it this direction it will be nationalized in order to bring it under government control.
2) The radio aspects are straight forward. As others have mentioned the satellites are just 340 miles away which is about 150 miles closer to earth than Iridium satellites. People have had Iridium satphones from even in the last century :-). Data bandwidth is better with Starlink and satellite to satellite links look like they will work.
3) Starlink is very difficult to jam (ask the Russians). The reason is that the comms are up/down versus side to side so jamming horizontally (typical) has no effect. That said, there are mixed reports of "ddos" jamming which is to say putting a bunch of ground terminals together to suck down bandwidth. As SpaceX retains the capacity to disable individual ground terminals at will this can be manually managed so it is a stop gap effort at best. Serious jamming efforts will probably be devised (a phased array antenna with a decent microwave power amplifier could probably "blind" all of the satellites in 'view') but that will take a while to happen.
4) Phone providers (Verizon, T-Mobile, AT&T, Etc.) who are still paying off huge debt for the billions they paid for cellular spectrum in various regions will mount a political attack on the effort. I expect submarine campaigns suggesting that Starlink "defrauded" the FCC with its original spectrum licensing requests etc. Random prediction here is that SpaceX ends up making some big payout to spectrum holders to offset the "lost value" of their spectrum investment.
5) And finally, it isn't particularly useful if you are inside. And very much not useful in tunnels/subways etc. We might see a reversion to an old cell concept where the antenna is on your car and your car is your own personal cell tower for your phone. Would not be surprised at that. Also existing cell providers have supported relays in subterranean spaces for a while and I would not be surprised to see SpaceX join them in doing that.