I have heard, no wasted words in writing. Which to me means, keep it lean and to the point. But sometimes you want to add flourish to your story. I am not sure when it's ambiance and when it's just added fluff, or filler words to crank up the word count. I like having the ambiance, the little tid-bits of your characters or the atmosphere that make them...who or what they are.
But when is it too much? Or too little?
My crit partners and I have had this debate in our critiques. And every one has a different ambiance threshold and even then it can vary scene by scene. I just finished the print galley edits for
WRONG TURN, RIGHT COWBOY; when I did the edits for the "E" version, my editor had me take out this really short scene. It didn't lend to the storyline at all, but to me, it was a character spot for the hero. I took it out, and as I did the print galley edits I debated putting it back in, but left it out again--'cause I just don't know. I honestly don't think the story is better or worse with it or without it so in that instance I deferred to the editor. Had I been more attached to it, I might have fought to keep it in.
Sometimes you, as the reader, want or need the flourishments--especially in particularly fast-paced books. It's your breathing space. Sometimes as a writer, you don't want them to breath just yet and you keep it simple, clean and zipping through to get the reader's heart rate right up there with the characters. You just have to figure out the balance.
At the same time, I have to admit, I very rarely read descriptions of characters in stories--I like to imagine myself as the heroine so it really doesn't matter what she looks like; and the hero will always be my hunk-of-the-week (as of late, that'd be Alex O'Loughlin... mmm-hmmm). There are times when their description is pertinent to the story, so for that possibility I do skim them a little, but by and large I gloss over it--she's gonna be 5 foot something, 30 something, not-eve-thinking-weight something, blondish with freckles. Every time.