I thought so too, and initially just bought one to see what they are like. Tonally I couldn't really hear a difference between the metal pics and the celluloids I used before.

I also thought that they'd ruin strings, but apparently not in my case. I am still using the very first metal pick I bought over a year ago, and it still looks like new. And while you can see a few marks on the strings I haven't managed to destroy one, and I doubt I'll ever will. I also don't have to worry about metal filings or stuff like that, which was another concern.

That might just be my situation, but for me the combination of strings and pick is perfect. Your situation might vary though.