The service is in beta, but looks to work the same as it does in the US. Purchases are tied to Amazon accounts, with games downloadable immediately after purchase, or as soon as they're available if pre-ordered, ready to be downloaded on release day. Amazon provides product keys and activation codes, which may need to be redeemed on a third-party client like Steam or Origin. Customers can re-download games from their Amazon libraries, but as ever, digital rights will vary across different products. You can also get in-game content via Amazon's store, if you so please - and maybe you do.
In terms of launch offers, Ubisoft's stepped up with a two-day sale that includes the excellent Far Cry 3 at £10, while Borderlands 2 is going at the same price on Mac.