Okay, uh... let's start with the positives I guess.
I think there are a few neat world-building wrinkles in episode five. I'm a sucker for anything involving slimes, so the slime info dump and the dish made from them was good fun. I enjoyed the bits regarding this land being more western in style with naming conventions and the comedic beat of Kazuya realizing this. It also sets up a neat little alter ego/secret identity in the form of "Kazuya" for when he needs to go undercover. I also thought that Ikumi Hasegawa's performance as Aisha during the last scene was good, with her slurping noodles and talking with her mouth full adding that extra bit of texture to her line delivery. Souma realizing that polygamy is the norm in this world is kinda great. It's presented as a very practical "yeah bro it's normal here?" – a rare moment where Souma finds himself intellectually on the back foot and not automatically telling others how things should be.
The rest of the episode was... less enjoyable for me. Much of the first half of the episode was the cast slurping noodles or planning a date for Kazuya. Perhaps it would have been more engaging if I felt more attached to the cast, but at the moment I don't feel like I know enough about them to appreciate downtime scenes like this. Low tension scenes can work for me, but I either need to be more familiar with the cast or more character development needs to happen in these moments for them to really pop. I simply was not engaged for the first half or so.
When the date proper started to ramp up is when things began to happen, but not in the way I was hoping. Look, I'm just not a fan of harem stuff as a rule. I didn't like Tenchi Muyo! when a friend begged me to check it out in the '90s, and in the decades since I haven't found it any more appealing. Aisha absolutely throwing herself at Kazuya with the "please use me" stuff, the cast sitting around talking about which day of the week they'll have... I dunno gang, I get that a lot of people enjoy this stuff but it's not for me. I guess all I can do is hold out hope that the cast ends up being more distinctive than their hair color and their day of the week in Souma's schedule...