As I continue to research my ancestry through DNA, using various tools and services, and gaining experience and perspective, my views of DNA services evolve. These are my thoughts about 23andMe at this time, nearly three years into my DNA research.
Pros:
(1) The biggest advantage from 23andMe is that they provide DNA-related health and trait reports, both interesting and potentially important. (23andMe is not authorized to provide medical information, but a 23andMe report would certainly be a good basis for seeking medical advice from your doctor.) They offer different analysis products, and I believe the least expensive does not include health reports, so make sure to order the level of analysis you want.
(2) 23andMe has a large number of DNA contributors. I have found many known relatives there and have identified many matches. Though my already well-developed family tree has made that easier, perhaps, than for others.
(3) 23andMe provides a list of DNA matches in common (ICW), as do the other services. They also indicate which of your common matches "triangulate", a much higher level of confidence that a match is related. On the ICW list are shown, too, the relationship of your principal match to you and to the ICW. (MyHeritage does this; Ancestry and GEDMatch do not.) Sometimes it is necessary to construct trees for your matches, a slow, labor-intensive process, and information about how some ICW are related to each other can help enormously in focusing on fewer possible branches.
(4) 23andMe uses a prominently displayed star next to each match in your primary list of DNA matches, that you can toggle on or off. This is very helpful for showing which matches you have placed in your tree. (Browsing through matches for matches to work on next, it's very helpful to easily see those already completed.)
(5) Ethnicity estimates seem as accurate as any, at least for my very homogenous ancestry. I think my best estimates come from my own family tree.
(6) 23andMe analysis includes the X-chromosome, which others do not. Since males inherit X chromosomes only from their mothers, a match on this chromosome can make tree research easier by eliminating some lines of ancestry. This has not led to identifying a match for me yet, but it is one more analysis tool.
(7) While they do not provide a detailed analysis of the Y-chromosome, they do identify a paternal haplogroup for males, which is a pattern found on this chromosome. Theoretically, this could be another tool to help connect to male relatives. In practice, I find it confusing because some haplogroups are closely related and a father and son may be identified with different haplogroups. If you know enough about haplogroups to recognize those that are closely related, perhaps this is not a problem. So I list this as a pro because it could be a useful tool, even though not yet for me.
(8) 23andMe has so far tolerated the use of third party tools, like 529andYou, to help gather DNA match information. (529andYou gathers lists of triangulations.) Though recently there has been more use of Captcha to, I assume, distinguish between people using data collection tools and robots.
(9) Though the lack of tree building is listed as a con below, the associated pro is that the user profile allows you to list birthplaces of your grandparents and family surnames and a link to a tree located elsewhere. This is enough information, often, to start a tree that can be continued by finding grandparents in census records (currently born before 1940).
(10) 23andMe allows you to download files for your raw DNA analysis, your matches and your shared DNA, which can be used for your own analysis offline.
(11) 23andMe seems to show matches down to about 7cM. (The bigger limitation is, perhaps, the number of matches displayed. I believe that MyHeritage and 23andMe limit the number of matches displayed, to about 8000 and 1000, respectively. When you have long-time American families, like my Dad's ancestry, these limits are reached before you reach the lower shared DNA threshhold, so there are not many matches shown below about 8cM. Ancestry's limit is, rather, the lower DNA match threshold, which they recently raised from 6cM to 8cM. All of these limitations are to avoid overwhelming [most] users with matches well beyond their interest and to reduce the load on their servers). So this could be a pro or a con.
Cons:
(1) 23andMe is not a genealogy service. There is no sister company with historical records, there is no family tree building feature. As part of your descriptive profile, you can list family surnames, your grandparents' birthplaces, and a link to your family tree. Personally, I don't need the paid access to historical records and have a public family tree with a link, so don't find this "con" a disadvantage. However, the lack of trees does make research quite a bit more difficult and I find my self searching for relatives more often on Ancestry and MyHeritage because of this.
(2) Managing or researching others' DNA can cause confusion. I have access to some DNA tests. Because I don't want to be seen as impersonating someone, when I send a message to a DNA match I explain that I am not their DNA match and what my relationship is to their match. Then I send a message, but since it's not my account I'm not sure how the message sender is shown. I usually include an outside e-mail address to make communication less cumbersome. Ancestry makes it easy to assign a management role to me. (Though I'm not sure how clearly communications are identified with them, either.)
Overall, I generally recommend this service, especially if you would like to get DNA-related health and trait reports.
