I am of mixed opinion. I think some of them are excellent places that are very enriching for dogs, but the good ones are hard to find.
My husband and I work full time during the day with relatively long commutes. A normal day has me leaving at 7am coming home at 6pm. My husband's schedule changes daily, however, and he can leave as early as 4am and come home as late as 6:30pm.
Our newest addition, Ember, does not like to be crated during the day (she sleeps in her crate at night and has no problems - she goes right in as soon as she hears the sleep music put on and waits for her dried liver treat that she only gets when she's in the crate). During the day if she is in there she tears apart her bed. When we tried gating her off in the kitchen instead, she chewed up the cabinets, baseboard, and dug holes in the walls. I started to look at doggy daycare places and could only find one that would fit my crazy commute schedule, and so I began to take her there. I am not 100% happy with it. It really depends on who is working. Some of the techs really try with the dogs and Ember comes home totally happy and relaxed, sleeping right after dinner, pretty much. Other days she comes home just as crazy as always and I am of the mind that they just kennel her for most of the day as she can be a handful if you don't work with her. One day I was able to pick her up early, while they were still in the daycare room, and I saw about 20 dogs in there with one tech just meandering around with his arms up, while 5 of the dogs - Ember one of them - just jumped up and down barking like crazy trying to get to his hands.
For us, doggy daycare is almost a "necessary evil". I don't have any other option as she has to be crated if we aren't home, and they don't allow people in to the house that aren't my husband or me, so we can't have a friend over or a dog walker in to let her out and take her for a walk during the day. Right now I try not to take her more than 3x a week, but even that I think is too much. I think she is much happier at home (just not in the crate) and it's confusing to her since I only take her and not Riley (since he has extreme stranger-danger issues).
There is one daycare that I would love to take her to that many of my friends take their dogs. They are one of the better places, that have onsite trainers and play with the dogs, take them for walks - they even have a doggy pond for the warmer months. I think because they have actual trainers onsite that I would even be able to take Riley. But unfortunately they are too far away and I can't make it there during their drop off and pick up hours.