I have quite a lot .co's for 2-3 yrs. Yes they work well, some of them #1 in SERP worldwide. The CTR is fairly good, ppl confuse them with .com's. Still .org, .net and sometimes .eu I value higher. .co can be targetted at WT.
The small bad thing about them is that they are roughly 2.5x more expensive and they can be extended only for 4 years at once. Also .eu or .me is safer if you are afraid what USA will do, because even when it is Colombian domain, USA do have some influence over it. Some .co domain was seized for Kim Dot Com which shocked me (same case is .tv and .cc). Also if you create brand then lot of your traffic will end at .com domain, much more than with any other extension.
If you talk to God, you are praying; If God talks to you, you have schizophrenia.