Your wife has/had cantilever brakes. They are reliable, but not too strong. They won't stop you in an emergency, but they'll help you avoid moving violations. You can get tickets on bicycles for running stop signs and lights you know. Plastic brake levers are by far the worst. Buy new ones asap.
The derailleurs are only sometimes put on right. Kent is one manufacturer that designs their bikes around the average wally world assembler. The derailleur mount is screwed on, and the angle is held by the axle, as on several other Walmart bikes. However, it is easy to cross thread the actual bolt that attaches the derailleur. These Walmart assemblers don't always get that right.
One other thing to check with all Walmart bikes is whether or not the bearings are properly greased, or cracked. I had a couple cracked bearings in my Kent bike, and within a few weeks, they broke completely.
So, all in all, I agree with Jason. Be careful with wally world, their bikes are very hastily assembled, and they will need a good preliminary look over. One other thing, the stem will sometimes be loose or crooked. Check to make sure it's not.
