If you have a listpage, at least in AX2012 RTM, where a field is an enum you can try out this odd behaviour.
Say that you have the enum MonthOfYearId as a field in the listpage. Now if you press ctrl+g to get the filter row and type in Dec* to get all lines with December you will get all lines. The filter for the field will do nothing. But if you type Dec you will get all lines with December.
So when filtering you must know if the field uses an enum or is just a string to be able to use the filter. This is really bad.