I'm currently watching "Sebi" reaction videos and people are generally very positive about the song. Very few of them venture to guess what kind of result Slovenia will get with it, which is understandable given it's quite new for Eurovision. The ones who do actually do see "Sebi" qualifying and maybe getting a top 10 placing.
They mostly praise Zala's soothing voice, the atmosphere of the song and the addictive light beats.
Visually, some do like the presentation as is, others don't get it. A few suggested Gasper should do something, while Zala should smile and look at the camera because one potentially can't connect with them... And I strongly disagree with all of that: firstly, one doesn't need to look at the camera to do well (we have several examples of that, including Italy 2013 and Portugal 2017), secondly, them constantly looking at each other is the whole point of this effort lyrically and story-wise. On the contrary, I think it sets an even more intimate atmosphere, as if Zala was singing to Gasper and no one else, as intended. Thirdly, I don't think Gasper should actually change his routine either: while he additionally plays the part of the "musician" (versus the vocalist), he is essential to the chemistry going on. Having him do a headstand, push-ups or some other kind of unnecessary choreography would jeopardise the connection those two have on stage imo.
Personally, I would let them be themselves and focus my attention on the camera work and the quality of the backdrops and spotlights to make the whole thing look grander in Tel Aviv than it was in EMA without overdoing it.
On a side note, while rather alternative and fresh (for the contest), I think "Sebi" may well be spotify-friendly, which may be an advantage. It seems like people could be willing to play the song (on repeat) outside the framework of the contest.