I've unsuccessfully dabbled in gstreamer in the past. I was doing a project this weekend, and the comments on this thread motivated to give it another shot .. after a couple of hours (2-4ish?), I was able to get video off the Pi to my desktop (on the same LAN) but the performance was pretty bad. I didn't optimize much yet but let me summarize the key issues I experienced with gstreamer these last few hours:

1) Very little documentation; poorly explained pipelines. I tried to read what docs I could find but things quickly devolved into trying out random gstreamer pipelines posted in comments. People don't explain why they use one particular element over another. So it felt like whack-a-mole.

2) Installing gstreamer on the Pi was a breeze. I wanted to pull video off the connected camera and sent to VLC on my desktop. Sounded like something that would work out-of-the-box? Nope. Kept seeing lots of stackoverflow comments of people stabbing in the dark, getting errors (or have the thing just sit there and not work) with very little feedback on what was wrong.

3) I have very little indication of what is hardware and what is software accelerated in my pipeline. I have no idea where latency is coming into my pipeline.

Overall .. my modern expectation for software frameworks is "batteries included" .. it is totally reasonable for sophisticated software tools to be complex .. but gstreamer is just not designed that way. While I got it to work, I see massive latency (likely because my pipeline is inefficient) and degraded quality (no idea why).