I just went from Veneers to Crowns on my front 4 teeth. They don't seem natural looking. Should I have them redone? (photo)

I am assuming that the lower picture is of the new crowns. I would agree that the previous picture was more natural looking. Choosing an excellent lab is critical to getting optimal results. Communicating to the lab with diagnostic wax ups, photos, etc. is also key to getting back from the lab what you want. I don't think you are being picky or unreasonable. I would give your dentist the chance to rectify the situation. Discuss your concerns and expectations and hopefully he or she can deliver the smile you desire. 

You're right on all counts. Not only are they too square and blocky but the color is not nearly as good as your veneers. I suggest you discuss this with the doctor and if he can't solve this then you need a more experienced doctor to do this.

Crowns don't necessarily need to be bulkier than veneers. Is the dentist who did the crowns the same one who did the veneers? I would share your concerns with your dentist. They should be able to recreate a smile similar to your previous one.

this the depends on how much tooth surface it was removed, and also the material on which the new restorations where made, there are several really cosmetic materials that can be used on cases like yours to get to a more cosmetically solution. metal free materials are the best for this anterior cases.

I don't know your whole history, but I assume there was a good reason to go from veneers to more aggressive tooth preparation - crowns.  Natural looking all porcelain restorations are very possible and are preferred by most patients I encounter.  After 20 years of practice and a strong background in cosmetics, i have found there are only a small minority of dentists and labs that can produce these results.  The greatest challenge is the lab.  I would refer you to Jason Kim Dental Lab in New York City.  His prices for lab work are 5 times more than what most dentists are paying for lab work, but you get what you pay for.  If you have a competent dentist work with Jason Kim, you should get excellent results.