Satellite APRS works fine and the APRS side itself is no different than any other APRS station. The terminal and modem side is the same. The radio itself is the same, other than you use a different frequency.
But yes, it's not a constellation of vehicles to provide continuous coverage. There's a little bit more effort predicting when a satellite will come into view and where in the sky it'll pass over.
Then being in orbit means if the pass is well off the horizon you need to change the antenna orientation to face it. A vertical whip is usually completely deaf straight overhead, so you at least need to tip the antenna over or ideally use a Yagi to focus your signal and follow the satellite.
The satellite doesn't discriminate but stronger signals will prevail over weaker ones and things like Doppler shift can cause packet data corruption and just the number of hams sometimes trying to get a contact cause collisions. Also the pass might be 5 or 10 minutes so not a ton of time to get more than a message sent and acknowledged. Plus sitting there holding a conversation while others are trying to make contacts isn't courteous. Repeaters and spectrum are shared so you should definitely use it but be mindful of other hams, too.
I wouldn't call it hard but it does require the operator to do more than just push SOS and wait.
The professors and students at the Naval Academy are (or
were anyway, the USAF isn't interested in letting USNA hams fly any more payloads) heavily into satellite APRS:
