The most surprising effect of Mounjaro, at least initially was that it drastically reduced by desire to drink beer, and when I started, my drinking was at a very unhealthy level (beer calories being a major factor in my weight problem). But maybe I'm an odd case, as I had a real beer habit but don't like wine and very rarely touched spirits.

Actually losing some weight as well as cutting my drinking down, helped me with depression far more than SSRIs (which had previously led to even faster weight gain)

Unfortunately, the effects started to diminish somewhat after about a year on it, as if I was building up a bit of a tolerance to the drug. And then I switched to Wegovy (=Ozempic) after big UK price hikes to Mounjaro, and found it much less effective, started gaining weight again (winter/xmas didn't help). Switching back to Mounjaro at the moment, but having to slowly step back up from a lower dose. Not expecting to see the initial near-miraculous effects again, expecting to have to combine it with some actual willpower and more exercise going forwards.