Admittedly I haven't watched Simmons much, only some highlights on youtube and the pre-season games against the Sixers. But other than his occasional explosive drives to and scoring around the hoop, I'm really not impressed, even beyond his lack of ability to shoot.
I didn't see any signs of good footwork. It didn't seem like he knows how to use a jumpstop, which reminds me a lot of Jeff Green (no I'm not making a direct comparison). I didn't see any advanced dribbles or moves. He didn't look to be poised, which is understandable given his lack of experience, but it was downright terrible at times trying to force plays and make passes that weren't there. I wasn't impressed with his defense either.
I'm not impressed by the Sixers, with exception to Embiid who truly is a beast but his health concerns make him a huge question mark.