My current fav .45
is a S&W 4506 and is probably one of the finest handguns I have ever owned (that would include SIG "P" series, Beretta, and Ruger).
Yes it is a big handgun, but if you have experience with other full size pistols with 5" barrels, then you can probably get a good idea what a 4506 is like. no it is not overly big, nor is it difficult to manipulate when using. Again if you can manipulate the controls on a Beretta 92, you can probably work the safety and slide stop in a similar fashion.
As far as trigger comments go, it is a fairly common thing to hear that S&W auto triggers are rough, gritty, or the like. I have owned a few S&W in 9mm and currently have a 4506-1 and a 4516-2 the triggers for all of them were excellent, on par with my P226. Even my 915 that I owned some years ago had a good trigger.
Accuracy and reliability are very good. My particular piece has the adjustable sights and with these I have been able to "zero" the gun to my particular defence load... a great feature! None of my S&W's have so much as hicupped as long as I do my part. My 915 FTFed once when I was messing around and probably limp wristed the gun during firing.
Durability has long been a quality that the 3rd generation of S&Ws are known for. I do not expect to wear either of my current guns out, and as long as I replace springs, keep clean, and properly lube the guns will be passed down to future folks.
For too long the S&W line of autos have been the recepients of negative commentaries. Far be it from me to make accusations, but the truth of the matter is that you hear a rumor often enough, you eventually begin to believe it. S&W makes very good autos in the 3rd gen line up, and for a 4506 in very good condition for $350, I would say that you have found a good deal and to snatch it up.
God Bless!