I picked up the Walmart Schwinn Varsity about a week ago. I have been riding it every day for a few miles and I really enjoy it.
After about 1/4 mile I got a flat and shortly after fixing it the other one went flat, both were caused by the spokes. I swapped out the cheap tubes with a better pair and installed some rim tape and haven't had any more problems. The wheels were far from true but that didn't take too long to fix.
I usually average about 18-20mph but the top speed I have had on that bike at was 32mph and I will admit I was rather nervous being at those speeds on a Walmart bike but it handled just as it should.
The "vintage" shifters are a pain to deal with but I am getting used to them. The seven gears on the right thumb are pretty easy to handle but the two on the left can be tricky. The shifting still isn't as smooth as I would like but its getting better with slight adjustments.
The fit is far from perfect for me with the "one size fits...one..." but its not too far off, no major pains for discomfort, yet. The saddle needs to be swapped out for something better but that is no different then most bikes.
Overall I am quite satisfied with my purchase. It was $220 (or 2.5 tanks of gas for me) but I would suggest ordering it online so you can assemble it yourself for obvious reasons. Shipping is free if you have it sent to the store. This is not a perminant bike for me but it will do a great job holding me over until I finish saving up for the one I want, even after I get it I am sure I will still get plenty of use out of it.