This was her second performance in Israel; the last was in 2010. Like other international performers, Riri faced a vocal and loud series of absurd appeals from movements who wanted her to boycott Israel. And, like most (but not all) international performers, she didn't even acknowledge the boycott. 
This is the first ultra-massively large outdoor entertainment event I have been to and it will probably be the last.  I'm a little old for the volume (I stuck paper in my ears), the entertainment value is really lessened when you are so far from the stage that the performer looks like a small pink blur and you spend more time watching the video screen, and it's really expensive. For the same money, I can have several evenings of entertainment. It was worth it to say I was part of it: once.
We arrived at 5:00 or so for a concert that was originally supposed to start at 7:30. This allowed us to camp out closer to the stage, though it really didn't make much difference. Rihanna was supposed to come on at 8:30, or maybe 9:00. She started at 10:00 on the dot.
First up at around 7:45 was an hour set from some DJs called We Are GTA. I don't get electronic club mix: I liked some of the songs they were playing - dubstep, pop, grunge, rock - but they only sampled a minute or less of each song and they sped them up and added electronics over them, making them worse. Every two minutes they crescendo'd, paused for effect, and started a new beat. Every once in a while the beat was right and they had the audience; the rest of the time the audience was indifferent.
Every two minutes they tried to get the audience to do something, but always one of two things: a) wave your right arm above your head from left to right and back, or b) raise your hands over your head and clap. I get the clapping; I don't get the waving. It's pretty tiring keeping your hands above your head for an hour. In a symbolic moment, the banner advertising the band slipped off of the front of their control station about midway through the act.
We waited an hour and a quarter after that for Riri, and that's a long time. The moments drag on and on and kids begin to get tired. I don't know why there were kids there to begin with.
Rihanna's performance was spot-on, enthusiastic, and laudable. She really is a good performer. She did a lot of grinding, bending over, and shaking, and some occasional simple dance moves with backup dancers - she doesn't dance particularly much or well, but she was energetic and hit her cues. She sang over a recorded track, but she sang much of it live and she sang well. She's very beautiful. She wore a black bikini top and shorts/underwear and a black sheer half-skirt with heels. She smiled a lot and shimmied. She performed for an hour and a quarter with barely a letup (she changed her shoes once, that's all). Her songs have great beats and melodies. It was very entertaining.
She gave shout outs to Tel Aviv a dozen or so times, apologized for being late (apparently she had to take a dip in the Dead Sea and pose provocatively on the beach), apologized for being away for so long, complimented her Tel Aviv fans, and promised to return.
I thought it was as good a concert as Alanis', though I like Alanis' more. Why? Alanis didn't dance; she didn't even, apparently, know how to walk; she seemed to have trouble with certain notes; she's not particularly beautiful. But Alanis has depth. Rihanna sings well, and flirts with being soulful, but her songs and her singing are just "feel good" or "feel sad". Alanis' lyrics and singing are pure complicated, messy art. Rihanna is pure simple, clean (or dirty) entertainment. Both are very good at what they try to do.
The weather was perfect; just cool enough that the mass of bodies around you made you the right temperature. The night and the stage were pretty, and it was too loud, but not too too loud. Thanks, Riri.
 Several papers made mention of the fact that, while she called out Tel Aviv by name several times, that she never mentioned the country name Israel. And that she substituted in one of her lyrics "All I see is Palestine" instead of the actual lyrics "All I see is dollar signs". A) I didn't notice it. B) I don't think too much of it.
 I've also been to large indoor concerts of Alanis Morissette and Pink Floyd; somehow being indoors made it a little less massive.