I just got my M&P 45 full size a few months ago... prior to that my .45 acp pistol line up was comprised of a Colt Series '70 Gold Cup, S&W 4506-1, 4566, 4516-1 (did I mention that I really like S&W's?), and a 945-1.
I once had a Glock 29, but sold it not long after I bought it... did not like the .45 acp in that compact form.
The M&P is very comfortable to shoot, and I believe that is largely due to the great ergonomics of the M&P grip frame and the replaceable back straps.
Recoil is a bit more noticeable, but not as pronounced as what the .40 S&W in my G22 feels like when compared to my S&W 4006. Don't know if that made sense, what I was trying to say is in my comparison of the felt recoil between a poly frame and metal frame pistol for the snappier .40 S&W, the .45 acp in the M&P doesn't feel as bad... to me.