You can buy a stand alone Slingbox which will let you do more such as access menus like you were sitting in front of your reciever. Plus you can use it on other things in the future, its not tied to DISH.
You can add the $45 Sling Adapter which lets you watch TV outside your house, but its a different experience (but works fine)
You can upgrade to a Hopper with Sling which is a faster Hopper and has the Sling features built in, plus you can transfer shows from your DVR to your tablet. The Sling Adapter does not do this.)
Out of the 3 options none are a bad choice, it just depends on what your looking to do and how much you want to spend.