In order to make metamagic feats usefull I devised a simple rule to use them for my players. Seeing as Magicusers get shafted on feats and then the cost is way to high at times to use them.
The system is simple as a full round action a PC attempts to enhance one of their spells with a metamagic feat. They must make a spellcraft check to see if they succede.
DC= 10 + metamagic feat level addition x 5 + spell level.
example: Empowered Magic Missile = DC 21 10 + (5 x 2) +1
If they fail the spellcraft check then the spell fizzles out and is cast with no effect.
Out of combat a player may take 10 on the check but never 20.
With the new skill rules I believe that the base Dc can be increased to 15 + metamagic feat level addition x 5 + spell level
The players seem to like this and they have actually used Metamagic feats in combat.
I already use something somewhat similar in my campaign.
I recommend these conditions :
DC 20 +spell level +spell modifier.
(ex: DC27 for a maximized Fireball)
Cannot take 10 or 20.
The problem with giving "Good Stuff"(tm) in exchange for a successful skill check is that it's generally pretty easy to get a high skill check. For instance, in Pathfinder alone the following abilites add to skill checks:
bard's Inspire Competence
Destined bloodline's Touch of Destiny
Community domain's Aura of Prayer
Good domain's Touch of Good
Liberation domain's Inspiring Word
Madness domain's Vision of Madness
Nobility domain's Noble Blessing
Divination school's Diviner's Fortune
And the following abilities allow you to reroll a skill check:
Celestial bloodline's Conviction
Luck domain's Bit of Luck
Just my $0.02.
While it is true that they can try an d get rechecks those themselves
are limited and should be used only in dire situations. As it is the
metamagic system sucks and is fairly broken. I have played 3.0 for
years now always with magic users in the party and have yet to see one
of them use it until I put that rule in. I never made any sense when
the power scales so quicly with spells to sacrifice a higher level
spell for an enhanced low level spell. That coupled with a small
number of feats they never seem worth using.
I believe they have to be fixed in the new rules or they are pointless.
Besides why not make them have to roll to use their feat any number of other feats only work after a successful roll.
I've seen lots of sorcerers use Empower Spell or Energy Substitution to compensate for the small number of powers known.
And I've seen wizards use Extend Spell or Sculpt Spell, too (although Extend is pretty cheap to get in a metamagic rod).