It's mostly enjoyable. I think there's a decent variety of activities each week.
The companions are decent. I do wish there was a way to acquire past GS companions as I wasn't active during season 1.
The rewards are mostly okay. The dyes, however, are generally ugly and don't stack. I'd prefer either fewer dyes or ones that people would actually use.
The objectives are mostly okay.
I've completed 2 and 3 and found it reasonably easy to do so. I didn't complete 1 as I wasn't active then.
For the most part, I can integrate GS in my normal gameplay. Sometimes, it incentivizes me to do activities like World Bosses that I'd normally not do.
Mostly, my feedback is to make previous companions available. I also would like to be able to purchase more from the GS vendors. It's always very limited how much you can get during a season, even if you log on all 100+ days it's active.