My in-laws have been huge Schwan's customers for years. Most of the items are incredibly unhealthy. By that, I mean chicken breast injected with liquid "stuff" and other high sodium foods. Personally, I think the quality is on par with other frozen food. My husband likes the boneless teriyaki chicken wing things (they're like chicken nuggets) but they're terrible for you and now he's gluten free so can't steal them from his parents chest freezer anymore. My in-laws buy the frozen chicken breast fillets because they're "perfectly portioned and individually wrapped"...well, they're full of sodium liquid and when you cook them a ton of liquid leaks out. They're not just regular chicken breasts like from the grocery store.
Everyone seems to like their ice cream (we prefer Ben & Jerry's pints ourselves), their pizzas, and I think their rice bowls (??) are popular maybe. I know my in-laws frequently buy the teriyaki chicken wing things, chicken breasts (full of liquid), salmon fillets (which are low quality salmon, Keta I think? Which is considered chum salmon!), and I remember just seeing some turkey w/gravy box in their freezer the other day. They buy tons of other stuff also, but I don't eat any of it so I'm not sure what's good. About 4 years ago they had an offer for new customers to try $20 of free stuff so I ordered a couple of things and it was just gross...no different than other frozen meals/tv dinners at the grocery store. Now, they do offer a few healthy items like frozen veggies, but it's cheaper to buy those at the store.
Yes, you can order directly off of the truck when they show up at your door -- they don't carry all of the items on the truck, though. Sometimes they're also out of certain items so depending on what you want, you might be better off preordering. I do know that it's incredibly hard to get rid of them!!! They will NOT leave you alone if you decide to not buy from them anymore. My parents tried them a few times many years ago and they kept knocking at the door for years. When I tried the new customer promotion I had to stop answering the door because they wouldn't go away (after I told them I didn't like the quality and wouldn't be ordering more). It's also very expensive...obviously you're paying for convenience which is certainly worth something, but it adds up quick!