Really depends on what your current and anticipated needs are. I do a lot of graphic design, a little video and audio editing and find the M1 iMac is incredibly zippy and fast for everything I've managed to throw at it. The only thing that seems to slow it down is when I've got several user accounts running at the same time (work, home, and a third one my wife uses) and it hiccups for a moment right after switching. I'd consider upgrading to some new iMac would be if they finally released a bigger display, on par with the 5K Intel iMacs -- but otherwise I'm good.
Maybe your needs are more demanding. If you're on the fence you could always get an M1 iMac, try it out through the return window and make the call then. If it suits your needs, you could stick with it and know you can upgrade to an M2 iMac further down the road, when you could probably pick one up as a refurb or on sale.