Lots of brewers have used the Corona with reasonable results. However, it is not a mill specifically designed for milling grain for brewing.
There are also lots who use an imported mill such as crankanstein (check spelling).
Personally, I use one of the original MillMasters from site sponsor mashmaster, and it is a great mill.
Their latest release is the MashMaster MiniMill, and it has had great reports from lots of brewers on here. My son-in-law uses one, and he's very happy with his.
An investment in a quality mill is not that cheap, but if you buy the right one, it will last you a lifetime.