I first bought the G29 and it's my edc gun. It is reliable, although for me it doesn't feed reliably when using the full-sized G20 magazines. Some folks don't have trouble. I suppose I could go on-and-on about the G29, but the fact I chose to carry it most of the time when I have many other choices in the drawer probably says it all. It is fun to shoot, comfortable and of course, 11 rounds of 10mm firepower comin' atcha.
I also have the G20 and call it my 'nightstand' gun, although it's seldom on my nightstand, shame on me. It too is perfectly reliable--no more nor any less than any other gun I own--and is comfortable to shoot. For whatever reason, I don't enjoy it as much as the G29. I think I've grown accustomed to somewhat smaller pistols and seem to prefer them in many cases.
And of course, Glock's 3rd offering in 10 is now hitting the shelves--the G40 longslide. To my eye, Glocks start out butt-ugly and get uglier the bigger they get, and the longslide is the most grotesque in the lineup yet. But, I'm sure it's a fine range toy/hunting pistol and especially fun when equipped with the red dot.
The 29 is at the top of my list of useful handguns that I truly get along with. I personally put it and the MP45c at the very top of my 'recommended' list for ccw weapons. There's nothing 'overkill' about the 10mm in my opinion--one doesn't have to load the round to 'squirt the case out of the gun' levels to be impressive, and it affords a double-stack configuration and capacity that's relatively compact.
My opinion of 10mm Auto is extremely biased--for me and what I consider important, it is a Perfect 10 auto pistol cartridge; I don't believe there is a better choice a person can make provided they feel comfortable and confident with it. AFAIK, there is no better carry gun for 10mm than the G29--and I don't consider myself a Glock 'fan' by any means.