It is, in many respects, similar to the superior Restaurant to Another World. The premise is that Nobuyuki Yazawa and Shinobu Senke open up Izakaya Nobu only to discover afterwards that their front door opens up into a fantasy world.
Isekai Izakaya is a fun show to watch but never really more than that. Shinobu-chan is a lot of fun to watch, and arguably evil in terms of her near supernatural ability to always be right there with a refill for your beer.
The world building is fairly limited in that the world is essentially late middle ages to renaissance Europe with two moons in the sky, and the Izakaya Nobu is fixed in place. Against that there is a steadily developing cast of regular characters who add to the fun as the show goes on.
However the limited world building does mean that you don’t get to have as much fun speculating about the world as you do with Restaurant to Another World.
Whilst there are occasional threats to the independence of the Izakaya Nobu these are always resolved remarkably easily. In trouble for selling lager that’s reserved to the imperial court? Not to worry, the retired emperor will stop by for a meal and smooth things over.
Isekai Izakaya is also a short at about 15 minute episodes plus live action shorts after each episode. The odd numbered episodes feature a cooking demonstration, the even numbered episodes feature a food critic sampling the featured food in Tokyo restaurants.
A pleasant way to pass the time, and worth a look if either genre interests you.
 The same can be said for the other girls who end up working there.
 Which is interesting given that the Japanese setting for Iseka Izakaya is Kyoto.