Coldplay defiinitely sound like U2. Not every song. In fact, I wouldn't have even thought of the falsetto on The Scientist as sounding like U2. but come on...Buckland's ringing guitar sound is clearly similar to Edge's. The rhythm section is pretty basic, like U2's. and yes, sometimes Martin sounds like Bono, though if anyone I think he sounds more like Thom Yorke, and ultimately pulls off his own voice. Does Trouble sound like U2? No, not really. But White Shadows? Clocks? In My Place? Talk? Speed of Sound? there are certainly songs that come off sounding like U2. doesn't mean they're copying, but the similarity is there.
I think the accusations come with this COMBINED with stuff like the Speed of Sound video, Martin saying Bono-esque things, posturing like Bono, and the fact that they're pretty open about their love of U2... for example, Eno producing their album. the only reason this raises any eyebrows is because Coldplay is already associated with sounding like U2. If some other modern band produced with Eno, people wouldn't assume they were trying to sound like U2. or the lifting of the banks and cathedrals line - again, if some other band did it, people probably wouldn't even notice (though around here, who knows).
anyway, I think Coldplay ultimately have their own sound, and not every step they make is trying to be like U2. but there is a definite influence and in some cases what seems like blatant copying. Maybe not though, maybe it's just a coincidence. Either way I still like Coldplay, I ain't hatin'. just saying, I think some of these points are legit. although really, what does it matter? If they sound like U2, well good, then I can listen to more music that sounds kinda like the band I love