Not great, not terrible. Mixed production values have scenes either looking like the next Star Wars film release or the pilot episode of Firefly.
The Mandalorian's character is also uninteresting and comparably weak when facing literally any adversary: Wild cave dwelling rhino creatures, Stormtroopers, and even jawas. This character is supposed to feel mysterious and powerful. Instead, he gets knocked around like the smallest dog at the dog park. Even the baby Yoda gives him the, "Really? That just happened? You couldn't handle that?" look too consistently.
Through Episode 4 (latest release as of this writing), there are no interesting supporting characters either. Baby Yoda is cute but voiceless, the IG bounty hunter droid is funny but disappears 5 minutes after showing up, and everyone else was erased from my memory 5 minutes after finishing an episode.
Thus far, The Mandalorian is average at best. If it weren't for the Star Wars license, this would probably fade into the infinite void of mostly terrible 1-season Sci-Fi originals. I still think it's worth checking out for the Star Wars timeline filler, especially if you are a die hard fan, but I would not recommend snagging Disney+ for it.