First off, you get a 30% larger display and a 50% louder speaker, along with slimmer bezels, a nicer dial, flatter body and, most impressively, an integrated electrocardiogram.
Its fall detection feature, which uses the accelerometer and gyroscope, can also dial emergency numbers if needed. Read about all the improvements and what else you can expect in our Apple Watch 4 review.
These upgrades did come with a heftier price tag, originally. Starting at £399/$399 for GPS only, the Series 4 launched £70/$70 higher than the Series 3. For GPS + Cellular, prices started at £499/$499.
Now, however, Amazon's discount drop prices across a variety of GPS + Cellular models. The cheapest offer is on the 40mm option with a black Sports Band, which is now £451.28 – a stark drop from the £699 RRP.
There aren't any GPS-only options included in Amazon's Apple Watch sale, however. If that's what you're after, you can pick it up for as low as £299 from Argos.
Compare the prices on the Series 4 across all major UK retailers below or head to Amazon now for its Apple Watch 4 deals: