Many reviewers have noted how impressed they were with the construction of the bags! While there are some Loungefly designs that use softer fabrics, most of these bags are made of a faux leather that, while light, helps the bags retain their shape and doesn't collapse in on itself.
You can take just about any item on a ride as long as you can either keep it in your lap/at your feet or in the storage pouch on the ride. Thank you all for the responses, can't wait to wear my bag! Disney is easy, it's universal I won't ever take a LF backpack to.
The bags are typically made of faux leather (vinyl). Prices are typically in the $75-100 range. They're highly collectable (Loungefly is part of the same company that makes Funko Pop figurines), but beyond a very few rare styles, not particularly valuable.
Plaques. Each backpack, cross-body bag, and purse made by Loungefly has a branding plate, or plaque, that communicates the overall value of the bag. The highest quality (and highest priced) bags feature metal plates. These are the only ones found at Disney Parks.