Yes, I recommend avoiding relative links whenever possible.
/wp-content/uploads/2015/01/iamgename.png is a relative link, which means that whatever domain I am viewing the post on is prepended to that URL.
For example, if I’m at company.com and your post have /wp-content/uploads/2015/01/iamgename.png that works perfectly. I’ll see the image, because it’s at company.com/wp-content/uploads/2015/01/iamgename.png
But, if I’m subscribed via email, I won’t see the image, because my computer doesn’t have an image locally at /wp-content/uploads/2015/01/iamgename.png. Similarly, if I’m using an RSS reader at example.com, I won’t see the image, because it doesn’t exist at example.com/wp-content/uploads/2015/01/iamgename.png
Stick to absolute links and avoid relative links whenever possible. The only advantage to a relative link is that you don’t have to change any of the links if you every change your domain, but the links break everywhere else, and there are plenty of find-and-replace plugins if you ever do change your domain.
Relative links aren’t worth the headaches. 🙂
(Hi there kjodle, great links, sorry to double-up. I guess that’s what I get for re-writing this reply so many times.)