I’ve seen it selling in drug stores pitching benefits to all and sundry. While there have been small scale studies showing possible benefits in people with heart disease I’ve had my doubts. Yet the hard sell goes on promoting CoQ10 to the general public as a wonder supplement.
Medline Plus has a reasonable take on CoQ10 and lists the benefits of CoQ10.
I would think you are wasting your money if you take something for other than what it is Likely to benefit you (practically nothing in for normal individuals!). If benefits are only Possible (read: maybe) or under the Not effective category you would be better off saving your money.
There was a small trial in heart failure patients which showed an apparent benefit. But even then as per this critical article in SBM on Coenzyme Q10 for heart failure: The hype and the science, there is some doubt.
Bottom line: if you have ischaemic heart disease it may benefit you to take CoQ10, but the evidence is from only small scale studies. If you are a normal individual, save your money.