They're great. I've had one for years. I have steelhead on mine as I type this.
Main thing I can get you started with is be prepared to wait for greatness - meaning that it is far above average quality, but it takes hours. Low and slow is key with the traeger. Although you CAN crank it up and get it done as fast as a normal bbq.
I can put on a turkey at 160f at 5am and it will just be finishing at about 7pm.
I cook everything from steaks and burgers, you know the average grill food - to lasagna, pizza, veggies ect. anything you can cook in an oven you can cook in your traeger and it only makes it better.
I have the big tex and I can fit 3 whole fillet'd adult salmon on it at once!
Just wait until you do your first batch of meat, you'll be sold! You think corn on the cob is good on a bbq, wait till you try it on the traeger..
After you get used to the traeger it's truly hard to choke down anything cooked over charcoal or propane.