In general Walmart is...ok. Their shipping times are pretty accurate, though they will sometimes split up shipments and don't clearly inform you. It also seems like their shipping pipeline is a lot rougher on boxes than Amazon. I ordered a window-mounted AC unit and the box showed up wrecked - the unit was badly dented and never worked.
Like Amazon, they have the problem of "seamlessly" integrating 3rd party sellers into their store which means you need to look closely or 4/5 things in your order will arrive day after tomorrow and 1/5 will arrive in 2-3 weeks.
[1] Walmart is no picnic either, but only so many companies can ship me the random products I've gotten used to.