Spoiler: it will probably have exactly the same performance as the M1 Mini and M1 13" MBP, and a slight advantage over the M1 MBA due to being better cooled.
...which is perfectly fine as a replacement for the 21.5" iMac it replaced, which it should conclusively thrash - maybe not quite as thoroughly as the Mini/MBP beat their Intel counterparts because the 21.5" Intel iMac did at least have a discrete GPU.
What it's mainly lost is the ability to support 2 external displays, which is not good but probably not a dealbreaker for the target market. The target market - especially for the cheapest model with just the two TB ports and no Ethernet - probably won't care about the ports, either. The two TB ports presumably - like the other M1 machines - each have a separate controller now, so the I/O bandwidth has doubled c.f. the 21.5" and now you can get more TB ports via a hub. (I'd prefer more ports but, frankly, using a hub/dongles with a desktop isn't as stupid as with a laptop where you have to carry them around).
However, Apple need to get a wiggle on with the M1X/M2 whatever, and the "pro" Macs using them.