I've frequently ordered items from Amazon Germany and found that it works as good as the UK site. Obviously postage can be a little longer but only very slightly than the UK.
Prices can be really competitive by paying in Euro just make sure you have a fee free card to avoid any currency charges although often Amazon translates this into £ for you.
There can often be discounts just like the UK site offer, such as flash sales or discount off Amazon Warehouse or application of coupons. In essence, you get all the services of the UK site. I've never had the need to return an item or contact Customer Service of the German site.