in my opinion, ROSCON is definitely worth it because of one main reason: you will be in touch with other ROS Developers and generate a ton of ideas from conversations with them. It is difficult to meet such amount of people that are interested about the same subject, and share with them opinions and ideas. This has tremendous value.
About the talks, well those are very cool, but you can always watch the videos later at faster speed.
The level of the speeches is usually very high.
About the workshops, well it depends on who delivers the workshop. I think that this is the weakest part of the conference. For me a workshop is something very practical, where you go to learn to do something new, not just to know about some things. Most workshops are just focused on a description of ideas (a guy talking), which is nice, but which leave you almost empty after the workshop is finished. If you are lucky and go to a practical workshop in which you practice and do something, then is definitely worth it. Otherwise, you can just watch the video later at faster speed.
In any case, ROSCON is definitely something you must check if you are in the ROS world, either attending to it or by watching the videos later. You should not miss it.