Both as a dm and as a player, I love metamagic feats. However, since 3.5 psionics, I've thought that spells should have built-in "augments" like psionics, so that you do not have to use a feat slot up to employ them. I wonder if 4e will head somewhat in this direction; I feel that quicker feat acquisition is almost guaranteed (but that might be the influence of the many folks here that have tried it and loved it; my group did too in my low-magic campaign).
Anyway, in the games I run, pc spellcasters often take metamagic feats. Not always, but often.
Some of the more popular ones seem to be Extend, Maximize, Empower and Quicken Spell. I have seen a lot of other feats get taken one or two times (or used 'em once or twice for npcs). However, there are some metamagic feats that I have never seen a pc use, and have never used as a dm, including Widen Spell. I think it must be hideously overcosted
I also think some metamagic feats could use a serious rethinking as to the level offset cost. You're already "spending" a precious feat slot on the ability; some of the weaker metamagic feats might be okay with no level increase at all, for example.