In case you didn't see it, Steins;Gate was one of the strongest shows of its time. And if you did see it, you likely know the main reason why, namely its lead, the inimitable Rintarou Okabe, aka Mad Scientist Kyoma Hououin. It did have a unique premise and gripping plot twists, but really, it was all Okarin, and to a lesser extent, the oddball characters surrounding him.
Put plain, Steins;Gate was carried almost entirely by a single character.
So far, Robotics;Notes is proving to be similar in that regard, but I'm sad to say that it's got a tougher battle ahead of it if it hopes to retain our interest. Where its predecessor was still strong in the premise, plot, and supporting cast departments, Robotics;Notes is weak, or at least less strong.
That's the bad news out of the way, but the good news is that so far, it's proven just strong enough, thanks to a smooth execution, adept pacing, and people that are just plain likable. Just.