A solid Roku box with a limited audience
The Roku 1 has always been a curious box in Roku's lineup. When it launched, it wasn't quite as cheap as the (soon-to-be-discontinued) Roku LT, and it's also lacking a standout step-up feature, like the headphone jack remote found on the Roku 2 ($80). Other than the boost to 1080p output over the Roku LT (which isn't particularly noticeable on most TVs), the wasn't much of a reason to buy the Roku 1.
Now the Roku 1's appeal is even less clear now that the company has introduced the new Roku Streaming Stick ($50). Sure, the Roku 1's price has been reduced to $50, but the Streaming Stick offers all the same features in a smaller package, plus it includes an RF remote, which means you don't need to point it at the box for it to work. The Streaming Stick will also support dual-band wireless and YouTube out-of-the-box; the Roku 1 and Roku 2 aren't slated to get YouTube support until later this year.
There are two main reasons you might opt for the Roku 1 over the new Streaming Stick. One is universal remote support. Standard IR-based universal remote controls won't work with the Streaming Stick because it's hidden behind your TV, so the Roku 1's traditional box is an advantage in that case. (However, Logitech has said it may add the ability to control Roku boxes over Wi-Fi on products that use the Harmony Hub, such as the Harmony Smart Control.)
The other reason is if you need analog analog video output. The Roku 1 is now the cheapest box with legacy analog connections, so it will work an older TV that has a composite video input (i.e., the yellow video port.)
Otherwise, the Streaming Stick looks to be a superior product in just about every way, especially if you're ever tempted to grab your Roku and bring it to a secondary location, like a relative's house.
Roku boxes compared
For a deep dive on the full Roku experience, check out CNET's full review of the Roku 3. Below is a breakdown of Roku's full product line.
Roku 1 ($50): 1080p video; HDMI and analog video outputs
Roku Streaming Stick (2014) ($50): smaller form factor, adds RF remote and dual-band wireless, YouTube support out-of-the-box.
Roku 2 ($80): adds Wi-Fi Direct remote with headphone jack, YouTube coming later this year.
Roku 3 ($100): adds dual-core processor, motion control remote, Ethernet jack, USB port, SD card slot; no analog video jacks; YouTube currently supported.