Apple's iWork '09 Numbers spreadsheet is a versatile app with a lot of power available if you open your mind and don't expect it to be Excel. It does not quite do everything Excel does, but it handles UTF-8 well (where Excel does not and has never), and I take advantage of that often. I also love the formatting options and the multiple-sheets-per-document paradigm, but that is a different post.
One challenge in both Excel and Numbers is how to handle fields with numbers with leading zeros. For instance, a part number 001234 will come out as 1234 when you import it from a CSV in either app, and lose meaning if the actual part must include the leading zeros. You can set a cell or column format in Excel as 000000, and this works the same way in Numbers, except the method's a little unfamiliar.
How to Format a Part Number Field to Preserve Leading Zeros