I love my sous vide machine! The best thing about a sous vide is you can't over cook something they way you can in an oven. If I'm cooking steaks at 132° and fall asleep, I could come back hours later and they would still be a perfect medium-rare. (This is also good for when my wife says "I'll be home in an hour" and looses track of time...) The only danger in cooking things too long is bacteria growth, and that rate will depend on the temp you're using, but it's many hours -- probably 6-8 hrs for steaks cooked at 130-140°. I've sous vide a leg of lamb for 48 hrs, and short ribs for 72 hrs. Those were both at lower temps than you'd use for steak, but you can do long cooks sous vide at lower temps without bacteria concerns.
I mostly do protein in mine, but my friend at work does veggies as well. My wife likes medium rare steaks and I always struggled to get the temp just right. Now, I almost always do them in the water bath. I put each one in a ziploc bag or a Food Saver vacuum wrap with a little olive oil, fresh thyme, salt, pepper and garlic clove or two, and drop it in the bath. I set the temp to 132° and let it go for an hour minimum. It's also great for cooking items that are different thicknesses, like fish. If you pan fry a fish fillet, the tail and sides get over done and the middle where it's thicker get under done. Sous vide takes care of all of that, because everything in the water will only equalize to the temp you have set. I love salmon cooked sous vide at 113° for about 40+ minutes. It comes out super soft and buttery, but falls apart easily, so be gentle with it. I normally apply some sugary glaze (honey, maple syrup, brown sugar & butter, etc.) and torch it for a few seconds to caramelize the sugar.
There's three downsides to cooking sous vide: you don't get the Maillard reaction, and since you're cooking at a lower temp, you can't make a pan sauce after you cook your protein, and they really cool off fast. The Maillard effect is what you see when you sear a piece of meat -- it's that brown and crusty bit on the outside. Not only does it look good, there's a tremendous amount of flavor in it. When you cook a steak sous vide, it ends up gray and it doesn't really look like something you'd want to eat. So you need a method to add the Maillard reaction to most proteins. My favorite way is with a blow torch. I have a MAP gas torch from Home Depot that I use because it burns cleaner than butane. I flip my cast iron skillet upside down, put the steaks on the bottom, and torch it for a min or so until it looks tasty. I cooked lamb chops sous vide recently, and I finished them on a super hot grill for a few minutes to get that smokiness of the BBQ as well as the Miallard reaction.
The pan sauce is easy enough to overcome if you plan ahead. You'll need to adjust your tempo a bit to make sure you pull items out of the water at the last minute. Protein cooked sous vide generally doesn't need to rest since the temp isn't above it's final target. But you do have to be quick about serving, as they cool off rapidly. I thought that heating plates in the oven was a good solution, until I broke one of the wife's favorite plates. YMMV. I don't heat plates anymore, so I just work to minimize the time between taking the meat out of the water and eating by making it the last thing to do: pull it out, drain it, torch it, serve it!