Except you would most likely have a high rate spam rate and a major number of recipients won't be able to see your content without downloading images first.
You will get a better response with a text only message.
LOTS of game related companies use the "image map" method because, as we all know, games are audio/visually awesome and cannot possibly be represented by plain text emails.
In my case the result is: Big red placeholder image and copyright text /unsubscribe link underneath it.
This might work for one off emails where your user base is expecting it. But try to A/B test the headline, or better yet customize it for each subscriber, now you have to make many variations in photoshop -> export -> map -> send. You could imagine this getting out of hand fast.
If you get a HTML template you can use mailchimp or exact target to put custom html to each subscriber / subset and do A/B tests. It takes more time up front, and limits what you can do (er outlook / gmail limits that) but if you get it right it will pay off down the line.
You will get a better response with a text only message.