Is this roast still good?

I would throw it out. 

Hard to say. According to the USDA website:

"After thawing in the refrigerator, items such as ground meat, stew meat, poultry, seafood, should remain safe and good quality for an additional day or two before cooking. Red meat cuts (such as beef, pork or lamb roasts, chops and steaks) should remain safe and good quality 3 to 5 days."

Sounds like it might still be safe depending on how long it took for the meat to defrost. If there's a lot of juice in the meat tray, a funny odor and/or it feels slimy, I'd toss it.

A week is pushing it, even for me. But assuming it looks/smells fine, I'd probably cook it well and then test it on myself before feeding it to children. Or you could just toss it and not worry about it.

I'll tell you, though, a large roast takes DAYS to defrost in my fridge. After a mere 24 hours, it would still be hard as a rock.

A roast in my fridge would take a few days to thaw. For sure. Americans are really cautious about their meat. If it smelled fine, I would cook it. I have cooked lots of things others would not have (sniff tested). We have never gotten sick from my cooking. I also haven't had a cold or the flu for years. Perhaps there is a connection.

Does it smell? 

My refrigerator stays really cold, and the meat bin is at the very bottom. 

My dh bought some steaks at the grocery store almost 2 weeks ago, and I cooked them on Wed. Night. They were fine and didn't smell at all when they were raw. Dh got the butcher to cut them specially, so the meat was fresher than what was in the case. 

Sometimes the meat in store can be a couple weeks old by the time it's sold. 

The Laura's Lean Beef stays fresh the longest. 

I wouldn't eat chicken that had been frozen and thawed and sat around in the fridge for several days. Chicken is also more likely to be contaminated with salmonella, etc. 

I would be more careful with ground beef, too, because there's more surface area that could be contaminated and is more difficult to cook well enough to kill off any bacteria. 

If the roast didn't smell at all, I would still cook it. Raw beef that goes bad definitely has a smell. I would sear it before roasting--I do this anyway because it adds more flavour. I also cook my roasts at 350 degrees. 

Cooking anything at 250-300 degrees lets the liquids sit in the danger zone longer. I like to put them in a hot oven and then reduce the temp. My favourite pot roast is browned then put in a dutch oven with browned vegetables and a mixture of wine and beef broth that was reduced by half. Then I put the roast, vegetables, a head of garlic cut in half horizontally, and a bouquet garni of thyme, rosemary, and parsley in the braising liquid and braised in the oven at 350--that is hot enough for the liquid to simmer well. You could simmer the roast on the stove, but doing it in the oven is easiest. There's no risk of the liquid getting too hot.

I'm another who is fine with it. It would take days to unthaw in my fridge. If there was no off odor or look I'd roast it and enjoy. 

I'm another that would probably use it. A roast at my house is usually 3-5lbs and would take about three days to fully thaw in my fridge. I'd do a sniff test. Beef has an odor when it's going bad.

I'd cook it. It would take a couple days to completely thaw in my fridge anyway. It it smells ok I'm one of those that will cook it.

I'd be willing to bet it took more than a day to thaw and it's probably fine. Most of our roasts are in the 3-5 lb range and they always take 2-3 days to completely thaw out when left in the refrigerator. The only time I'd worry would be if your refrigerator isn't the right temperature inside (38-40 degrees). We figured out ours was off when the milk started going bad a week before the expiration date!

I would throw it out, but I am super paranoid! I can't smell it because I don't have a good sense of smell. I was cooking chicken a few months ago that I bought that day and it wasn't close to the sell by date. My husband came home and said the chicken smelled funny, so we threw it out.

I do things like that too and get so mad that I "wasted" money.

This has been my experience as well.  I would cook it and eat it.