It took us a while before we decided to get a playpen. Like many of our "delayed" purchases, they turned out to be indispensible. It's not like we put DD in there for any great lengths of time, but it did come in handy for naps. We put her in the "basinet" portion for naps, and later when she outgrew that, we just placed her on the main floor of the playpen. She still naps in there at times. And the playpen was a convenient safe place for me to put her in when I needed to get the door for a package delivery, and stuff like that.
Oh, I just remembered one time after changing DD's poopy, I placed her in her crib while I went to wash my hands. When I had returned, she pooped AGAIN! This was back when she still had the "watery" poop, so it leaked and got onto the crib bedding. So I had to change her diaper a second time, and thank goodness I had the playpen to put her in afterwards so I could take care of getting the crib bedding into the washing machine.
DH puts DD in the playpen in the mornings for some independent playtime. She has some soft toys in there, and we even hung a musical toy off on one side.
The playpen was also indispensible when we travelled, it gave DD a safe place to sleep at night.