After the missed potential of Ultraman Trigger: New Generation Tiga, the Ultra series needed something fresh and rejuvenating while still exciting. Ultraman Decker, a reimagining of Ultraman Dyna, may have had a fresh take on Dyna, but it was anything other than rejuvenating or exciting.
For starters, the kaiju combat scenes (the scenes that made the Ultra series) were a complete downgrade from the last season. Comparing Trigger and Decker's first combat scenes, Trigger's felt more alive and ambitious, where as Decker's felt like a fight the should be in middle of the show. Decker's fights feel stale and seen a million times.
Now the character's are.....not great. They may seem like a huge plus over Trigger's, I personally found them either extremely boring or annoying.
Although, the show gives them episodes about the side characters, which would have been a plus over Trigger if the characters actually develop, but they don't.
Kanata Asumi, the MP, is very flat and can be very annoying (yes, worse that "Smile, Smile" Man himself at times). Throughout the show, the only personality trait the show established was that he likes to yell and he likes rice crackers (I think, I don't remember). I personally think the writer (Masayoshi Takasue) was trying to copy from Haruki (Z's MP) without understanding what made Haruki a good character. Ichika is (to put it mildly) the token stereotype anime girl trying to....well, something. She is easily the most annoying character of the entire series and her stand alone episodes don't do her any favors. If Ichika was the most annoying, then Ryumon is the most boring. He's basically acts as that strict older brother who kind of has a bone to pick with Kanata (but who doesn't). He's also kind of the opposite of all of Trigger's side character's combined. Trigger's side characters were all personality and no backstory, whereas Ryumon is all backstory and no personality. Kaizaki is easily the best part of the series, as she didn't come across as boring or annoying, and she also had a pretty decent stand alone episode. Murahoshi, the captain of the main team, comes across as the worst captain of any Ultra team. He behaves more like a creepy uncle than a captain.
During Trigger's production, many things were rushed and had a lot of studio interference on Tsuburaya's part, which can explain many of the problems that Trigger had in the end product. However, Decker does not have this excuse, so what can explain the lazy and boring mess we got. Here's one: Bad writing and direction.
Overall, Is it better than Trigger? No, it's not. In fact, it may be worse. Personally, I felt insulted watching it. While his series makes few improvements, it made way more mistakes in the process. I haven't gotten into the spoiler parts of the series, so you'll have to see yourself (although, I don't recommend it). Despite the bad characters, poor writing and weak combat scenes, what mostly infuriated me the most was one thing; It's Boring. If a Ultra show is boring, than it failed as an Ultra show.