Whatever you choose to do with this monetization and marketing technique, take time to plan your strategy. While it is very easy to get started and to add Amazon affiliate links to WordPress, the key to success is in how well you execute those links and promote them to your visitors. Affiliate marketing takes time to excel at, so be patient and don't give up!
Note: I think the line where readers will push back probably will vary from blog to blog depending upon their readership. For example here on ProBlogger I get a little more negative feedback from readers on affiliate promotions. I suspect ProBlogger readers are a little more tuned into the issue and suspicious of some of the affiliate marketing that goes on around the web.
Analytics are limited. Unlike with conversions made directly on your WordPress site, you’ll be limited in terms of what you can learn about the people making purchases through your affiliate links. While Amazon does provide you with details about clicks and sales, you won’t get deep insights into who the consumer was and what they did on your site before they got to that point that you would with Google Analytics.