Version 1.8
When I tried to edit the single product variant for a product I had imported using the Excel Import function, pressing the Save button produced no discernible actions. Through javascript debugging, I discovered the page did not validate because I had set the cycle length and total cycles to 0, even though this was not a recurring product. I also had "Notify Admin for Quantity below" as 0 (since manage Stock was "Don't track inventory for this product"). All these prevented the page from validating. However, there was no indication the page had not validated.
There are two errors here -- first, the excel import should prevent invalid entries, and second, there was no indication the page was invalid -- especially since the recurring product errors were hidden since I had not selected "Recurring Product" and similarly w/ "Don't Track Inventory ...".
Both problems are quite easy fixes -- the Excel Import should validate the data entry the same way the form would and/or correct default values, especially when the values in the field do not matter because they are not used (if no recurring product, for example).
The page validation should simply use a ValidationSummary control on any form that has hidden fields that could be invalid.