01 Bundle type coverage
Quantity breaks on one SKU, fixed bundles of different products, mix-and-match from a collection, and BOGO. Most stores need the first two; builders matter for supplements, coffee and apparel sets.
02 Inventory behaviour
Does a bundle sale decrement each component's stock correctly? Bundles sold as a separate SKU with manual inventory are how stores oversell.
03 Widget design control
This block sits directly under the price. It has to match the theme exactly — fonts, radii, colours — or the product page looks bolted together.
04 Analytics
Per-offer revenue attribution so you can kill offers that only cannibalise single-unit sales at a discount.
05 How the discount reaches the cart
Plugins that hook into WooCommerce's own pricing and coupon system behave predictably with taxes, other discounts and reports. Ones that overwrite prices directly tend to break one of those three, usually reporting.