Having been to Athens a number of times, Likavitos is one of my favourite places to go back to. Maybe its a nostalgia thing as it was one of the first places I took my wife on our first trip away together. There is something very romantic about sitting in the cafe at the top, watching Athens going about its business below you.
I know there are those who will complain about the funicular costs, the restaurant costs or the lack of things to do up there, and they are right. I would avoid the very pricey restaurant at all costs and eat in the much cheaper cafe, but the grilled chicken and mediterranean vegetables I had there were superb.
I, like others would recommend going there at twilight but if you get the opportunity, go twice, once in the day and once at night as they are two very different experiences.
My only warning would be to watch the weather. I got stuck in a thunderstorm up there, and being the highest point in Athens, the lightening was striking a little too close to me for comfort. Then when we got off the mount, we got caught up in some minor flash flooding trying to make it down to metro level. The water wasn't deep but we did have to cling to shop windows to make it down.
All in all though, I think Likavitos has an atmosphere that I've not found anywhere else (but then I'd say the same for Athens). If you're going with someone special, make the effort, sit in the cafe and get close whilst you take in the panorama and watch the sun set.
This review is the subjective opinion of a TripAdvisor member and not of TripAdvisor LLC.