Hinadori Girl is an episodic slice of life that follows the Ishikawa household. Yoshiki Ishikawa is the son of a genius scientist and "technophile" father, so the son naturally follows in his footsteps. One day Yoshiki starts up his father's robot Sari#1 (Sally number 1) and the series follows Sari as she "grows up" and learns what she can and can't do.
Story - Most of the story revolves around brother-complex (and tsundere) sister Akira Ishikawa and her jealousy over her brother's attention to the robot and the robot's love and clinginess towards Yoshiki (the brother), but the overplayed romance that'll never go anywhere (except that one time in Yosuga no Sora... and Myself;Yourself) isn't why it's rated 5. Inevitably, I've compared Hinadori Girl to Yotsuba&!, both manga are about a young girl growing up and the funny things they do but where Yotsuba is more consistently funny, Hinadori has only situational comedy which can get old.
Art - The drawing style is very good, although it does remind me of Pokemon, but that's probably because of the obvious Team Rocket parody by Tsukiko and Sasuke, the incapable "baddies" of Hinadori Girl.
Characters - Yoshiki Ishikawa is your run of the mill asexual guy who is only interested in robots, but he does appear to take interest in his sister towards the end although I can't confirm this as I can't find chapter 18. Akira Ishikawa is your run of the mill brother-complex tsundere type (think Lucky Star's Kagami crossed with Kirino from Oreimo). And Sari can only go so far when she can't speak. But still the characters are interesting enough to keep me reading.
Overall - Having said all those negative things, it's entertaining, it's funny and it's cute, despite appearing to be just another shounen manga this one somehow strikes above the rest with superior humour, superior situations and superior characters. The reason I've scored it so low is because I compared it to Yotsuba&! and there are no translated chapters past 17 (that I can find).