It's a... conclusive ending. However, there are several things that are unclear and confusing. So much so that I had to go and read the last chapters of the manga to see if that's how things were supposed to be. And NO. Everything makes more sense in the manga. In the anime, Chii, upon recognizing that Hideki is the most important person to her, enters a strange mode that affects the other persocoms in the city, disconnecting them. Someone reappears, and Chii makes a drastic decision, causing Hideki great distress. I won't say more to avoid spoilers, but know that it's very different in the manga. Freya questions Hideki if he would love Chii even if he couldn't sleep with her because her reset button is in her private area (So doing "things" with her would erase her memory). The chaos Chii caused not only disconnected the city's persocoms but literally caused the city to collapse, with thousands of things failing. (This isn't in the anime.) Chii isn't a legendary persocom; that's a legend people wanted to believe in, a way of hoping that a machine could exist that was different from all the others. Therefore, the fact that Chii is capable of love opens a window of hope that all other persocoms can do so as well. Read the manga if you didn't understand the anime's ending. I recommend it.