Summary: None thus far. The price was great for me and I am using this for a music studio for my teenager to mix music and with 16 GB Logic X works and is able to work better.
Pros: I was looking to upgrade the RAM from 4GB to the max. I researched a bit and found that I could go up to 16 GB and pulled the plug on this RAM. I have bought Kingston RAM's before from New Egg and they have worked well for me. I got it at a sale and paid $70ish for 2 x 8GB sticks.
Cons: No real cons except that at first the 2 sticks did not work together. I dont know if this was not properly seated but I tried one at a time and after I swapped the sticks with the slots on the mini Mac - dont think this had anything to do with this but worked. I was glad.
Summary: Upgraded Macbook pro early 2011 after I noticed a substantial deterioration in performance over the years. I ordered Crucial MX200 and a Kingston 16GB ram together. The package arrived sooner than the estimated delivery date which was absolutely fine with me.