They're not sufficient to count as legally lit simply because the law says it must carry the BS or equivalent European marking - unless it only has a 1-4Hz flash mode of 4cd or more, or if it's a headlight on a vintage bicycle. I don't think it entirely makes sense, but that is what is required to be legal and everything else is a matter of opinion (for example, I think flashing lights are daft because a motorist may glance when they're in the "off" phase).
Yeah, I've done my time grubbing along searching for the road with old D-cell lights and that's overstating it slightly but no, they weren't good. It's rather disappointing that lights now aren't absolutely perfect with the brighter LEDs, but they aren't.
Most commonly, the beam cut-off is too far above the brightest spot, so you have the awful choice of whether to aim it closer to your wheel than you really want, or to aim it where you want it and consequently dazzle oncoming road users, which is rather rude when it's a cyclist and inviting serious injury when it's a motorist.
There are a few lights with good lenses and no standard marking, but they seem depressingly rare. The cycling light market seems almost completely broken, with shops selling mostly awful lights marketed on meaningless lumen and Watt statistics, with most cyclists either not caring whether they're nasty to others or disagreeing that it is nasty to shine a light in others' eyes.
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