Personally, I don't like them. I want the flexibility to arrange furniture however currently best suits my needs, and a built-in closet permanently reserves a portion of the floor area. Stand-alone wardrobes also offer flexibility when occupants vary in how much stuff they have that is a good fit for a closet.

When we were adding dormers to our house four years ago we needed to decide whether to include closets in each of the rooms. Here's what the three new/expanded bedrooms looked like with and without closets:

Anna's bedroom

What will be Nora's bedroom once she's out of our room. Currently my office and where I sleep for the second half of the night.

Lily's bedroom

We decided to construct all three without closets, and in retrospect we're both very happy with that decision: each of the three has the bed in a position that wouldn't be possible if we had kept the closets.

(Sometimes people will say that it doesn't matter whether you like closets, building code requires them. This is a myth: the International Residential Code (IRC) says nothing about bedroom closets. And our building inspector had no issues with our closetless bedrooms.)