I have one with the 22mm and EF adaptor. I got it so I don't have to lug my 5D3 everywhere.
A lot of people here bash the EOS-M for what it isn't supposed to be. Those opinions are misguided because the EOS-M isn't supposed to be your DSLR substitute. What it is is a compact with impeccable image quality, full manual control, AF points you can virtually focus anywhere in the scene. And to top it off, can use EF/EF-S lenses! The EOS-M is for those wanting to jump in the photography scene but don't want to get a chunky DSLR. Eventually when those people buy EF/EF-S lenses it'll be a much more economical transition to a DSLR.
Sure the AF is slow - what do you expect from a compact??? But take note the AF speed depends on what lens is on it - STM lenses focus fast, while it's painfully slow with my 16-35mm II. EVF? You don't put an EVF on a compact. Me, I compose just fine from the LCD.
Take the EOS-M for what it is. If you want a smaller body that has proper AF speed, get a 1100D/650D. Or a Sony Nex if you have a lot of money to still invest in another system. Otherwise there is no substitute to the DSLR you currently have.