I have no regrets about testing at 23andMe, but that's because I was interested in the health information and raw data. In the long term, I absolutely almost-sorta-kinda totally hate it for genealogy.
I do think I got good value for what I wanted, and I'm very pleased to have found one solid match there who wasn't already on GEDmatch. So there's that.
The new ethnicity analysis is cool, but you get the same info via GEDmatch.
About the participant demographics, I've only had about six non-American matches there, but my most recent immigrant ancestors were ~200 years ago (with most further back), so that may well be just me.
The thought of lots of new customers coming in *seems* like it would be great, but it's not because 23andMe caps your matches at ~1000. I *started* at 987 the day my results came in, so I hit the limit very quickly. You do get new matches, but only at the expense of losing old matches who are not quite as close as the new match.
Apparently the "trick" is to request genome sharing from your lowest matches first, since they won't be replaced while the invitation is pending, but you'd have to madly send out 1000 invitations before new matches come in or else some *will* be lost.
Speaking of pending invitations, that's what my match list is full of: people who never respond. Many people at 23andMe are only there for the health report, so they ignore requests to compare chromosomes, and unlike FTDNA, the only way you can make comparisons is by individually messaging each match and hoping they respond favourably. I read an article about 23andMe where the reporter completely dismissed the genealogical aspects, saying something like, "Only royalty regards 4th cousins as being related." I think many of 23andMe's customers echo that sentiment.
GEDcom capability is pretty new at 23andMe, and pretty awful. (I can barely navigate my own tree on the site, regardless of browser, and I know what I'm looking for.) I know trees are bad at FTDNA, too, but this somehow manages to be worse. If you're lucky, people will put surnames in their profile. I highly recommend the Google Chrome add-on for 23andMe that makes shared surnames stick out.
My matches who have responded have been friendly and generous, but again, almost all of those who have responded have been on GEDmatch, too.
But! I did get that one match who wasn't, plus the health info and haplogroup, plus raw data to play with (and transfer to FTDNA), so I'm happy. I can't see how it's the right choice for most genealogists, even with the new price, but I do hope the new price somehow drives 23andMe to make a better site for genealogy.