Takeo is not famed for its culinary offerings, but you certainly won't starve. Aside from the lakeside place mentioned below, try around the Independence monument and the market for basic Khmer offerings. There are also a couple of places on Route 2 on the way into town, but we didn't sample them.
As far as sitdown places are concerned, the Stung Takeo has a comprehensive English language menu and great views out over the floodplain. While this is a great spot to escape the midday heat, the only oddity is despite all the beer posters that adorn the interior, the beer they serve is always warm. The food is all Khmer offerings with a couple of generic Asian dishes. Not surprisingly, the fish, is pretty good here. Very limited English is spoken.