Honda Accords tend to win a lot of 'Best Car' awards from a myriad of automotive journalists. They are, for all intents-and-purposes, a very good car. I've never owned one (or any Honda, for that matter), but I have a couple of friends that have owned them (Civics & Accords) and they really have never had anything bad to say about them. Mostly that they just run forever.
But no matter how reliable the make & model is though, you can't ever say for sure if one particular car will be good or bad. The best way to find out info about a particular car is to seek out a forum dedicated to that model. I'm sure they exist for the Honda Accord. A few minutes of searching will probably answer your questions of specific reliability concerns.
The biggest objective difference between an Accord and a G8 is the fact that an Accord is front-wheel-drive and a G8 is rear-wheel-drive. Never mind equipment, reliability or resale value, but an Accord is going to be significantly better in inclement weather (read, I see you live in Ontario) than a G8 will be.
As Nick said, the G8 has gotten positive reviews. By most accounts, it's a good car. It is designed and manufactured by Holden, which is a GM subsidiary in Australia. The G8 has actually been around for several years in Australia (as the Commodore) and in Europe (as the Vauxhall VXR). It has enjoyed favorable reviews there as well.
My personal opinion is that a G8 would be a lot more fun to drive than an Accord. Accords are great cars, but whenever I've been one (test drive or riding in a friend's) they seem to be lacking a little bit of "chutzpah". They're a little....appliance-like. For a lot of people, a car *is* an appliance. An appliance from getting from point A to point B. That's fine for them, but I like my cars to have a little bit of personality. I would suspect that a G8 (especially a G8 GT - with the 360hp V8 from a Corvette) would be a lot more fun to drive than an V6 Accord for nearly the same money. Given $30k and a choice of a V6 Accord or a G8 GT, I'd take the G8 GT.
I'd guess that an Accord might be more reliable in the long run. But to be fair, GM has made really significant strides in quality in the past few years. By many accounts, GM and Ford quality is on par with that of Honda & Toyota these days.
The only real downsides of the G8 (V6 & V8) over an Accord is the fairly lousy fuel economy and resale value. An Accord, even the V6 (19/29), is going to get better mpg than the V6 G8 (17/25). And Hondas have always enjoyed better-than-average resale value, while Pontiacs usually fare below-average. And especially with rumors of GM axing the whole Pontiac division, one never knows.
