Search under Maverick and you will answer your own question. This has been discussed a couple times.
Main points are that the Maverick is a Mossberg product, was a cheaper line of the 500 and it was assembled in Mexico, therefore, lowering the production costs of the gun and that's why you see a lower price. Cheaper parts and quality control.
From what I have read, it seems that the consensus is that it is a "cheaper" gun, ie, more play throughout the gun, not as durable and also is lighter, so you feel the recoil more.
If you like it and feels good to you, get it. Some people have said they loved their Maverick's and that they have held up well. Most people have said what I stated above.
I was looking at one also and had the same questions. I ended up getting an 870, simply for the fact that the shotgun will more than likely outlive me. A $100 or so is worth it to me to get a quality gun, with a solid reputation that will hold up and be there for me when I really need it and also be there for me down the road.
Just my .02 though.