I just added all of the achievements for Gears of War and I had some things/thoughts I wanted to post.
2. The text for the "is secret achievement?" appears below the check box instead of next to it inline. Priority: very low.
Note: I used chrome for my browser, but I verified it does the same in Firefox.
3. Not really a bug, but I noticed that the secret achievement attribute didn't seem to make a difference on the display in the list of achievements. Also on the page for the achievement itself, there was nothing indicating that it was a secret achievement. I assume that this is for a future enhancement (like hiding details on secret achievements), but for now the achievement page should at least have a line saying it is a secret.
1. It would be nice to have a button on the page after you have created a new achievement that lets you create another achievement for that game instead of having to go back to the Achievements page each time. Not a big deal, just a "nice to have" suggestion.
2. For games that have DLC with additional achievements, it would be nice to see on the achievements page in the table an indication that this is a DLC achievement. Perhaps a small DLC icon next to the achievement icon or automatically placed next to the achievement name. This could be later integrated into the idea you already posted about grouping or subdividing large achievement lists by category, i.e. DLC would be a category.