This will be an interesting anime to review.

In the four Isekai worlds of Konosuba, Saga of Tanya the Evil, Re:Zero and Overlord, a mysterious button sends the casts of all these anime to a school setting, with no way back until they show that they can live a school life, the colourful cast unite in many of the typical scenarios associated with a school comedy.
A series like this is what's known as an SD omake, or super deformed omake referring to the cute designs of a normally vibrant mostly serious cast of characters.
The original quartet is later joined by the Shield Hero and the Overpowered Hero from season 2 onwards.
The combination of casts mix surprisingly well with the Isekai'd protagonists trading stories of how they ended up in their worlds, other than Konosuba and maybe the Overpowered Hero the other shows are more straightforward originally, Tanya the Evil is probably even more serious, so bringing them all into a comedy world does give you a unique perspective of each world's cast.
Surprisingly it's Tanya the Evil that comes out as the breakout character from the show which will probably make that actual anime harder to watch.
I won't rate the dub as I've not seen all these shows separately to offer that perspective.
Final Verdict: Not much to say really, it's just a gag comedy that passes the time between bigger anime.