As for the ratings, you need a bit of context there. Ultraman Ginga aired in the same time slot as Ultraman Retsuden, which is basically just reairings of old episodes, so its ratings have always been low. Ginga wasn't likely to do much better.
Yeah, 0.3% below the first Retsudan is the most relevent comparison really. Of course, with Bandai being major shareholders iun Tsuburaya now, they're probably more concerned with the merch sales than TV figures.
Ginga had a lot of potential. Being like Decade and Gokaiger, where he can change into any Ultraman or Ultra monster. The concept is surely entertaining. But they really didn't do well at all. The actors suck. I feel that if Tsuburaya had a bigger budget to fund for a full year length series it would be a lot better.
[HIDE]I think the acting was restrained by the amount of money they had, rather than the ability of the actors. It's really obvious when watching the show that the actors didn't get a chance to have any rehersals, and they're filming every scene in just one or two takes. So you basically just get an on-set read-through, as nobody has heard the other cast members speaking their lines aloud before and so doesn't really know how to play the scene or have time to develop any chemistry. I'd love to see how some of these actors perform in better circumstances. As it is, it really makes you appreciate just how slick Rider and Sentai are on that kind of level, even if Toei is well-known for their insanely intense scheduling.
Similarly, a lot of the action scenes are quite obviously "one take wonders". IIRC the low visibility podcast mentioned that there's a shot of an alien falling down, where the suit actor is accidentally wearing the alien's head backwards! I think showing Ginga off, and the gimmick generally, was held back because they were constrained by available suits, minimal effects, and a simple lack of time. As a result the fights are short and pretty straightforward, rather than being able to fully take advantage of the gimmick.
The other weird thing about Ginga is that (perhaps because, as I said above, Bandai are now a major shareholder and they demanded that it be something that promoted the toys in the manner they were used to) it's taken on a lot of elements that feel more typical for Rider. A teenage hero who investigates cases of people turning into monsters with his school-aged friends, then uses a toyetic transformation trinket to become the hero. Completely normal for recent years of Rider, but not normal for Ultra.[/HIDE]