This is an interesting subject, and you can spin the current situation in different ways. I feel that Spell Focus and Greater Spell Focus are too weak in 3.5. My spin on points made by other people is as follows:
A. Anybody can increase all three of their saves by +2 with three feats. For a spell caster to increase all of their DCs by +2 requires 16 feats, 2 per each of the schools of magic.
B. A fighter gets +1 attack bonus with a weapon of his choice for one feat. But, the fighter will use that weapon for the vast majority of all his attacks. In effect, he gets +1 on all attacks for one feat. And he is probably going to take Weapon Specialization that weapon, which is clearly superior to Greater Spell Focus. If the wizard wants to get +1 DC on all his attacks, he needs 8 feats, one per school.
C. Somebody said that the wizard gets to pick the save being used. Which means nothing unless he has Greater Spell Focus in all the spell schools. So the Evoker gets to use a Will-based spell against the dumb fighters. Um, exactly which Evocations have Will-based saves?
My last argument is to use my existing Epic druid character, regress him to 12th level (which seems to be the accepted comparison point for this argument), and convert him and his self-made items to 3.5.
Relevant attributes:
CON: 16 + 1 (inherent) + 6 (self-made amulet): 23
DEX: 12 + 6 (self-made gloves) : 18
WIS: 18 + 3 (inherent) + 3 (levels) +6 (self-made headband): 30
Other relevant items:
Cloak of resistance +4 (self-made)
Stone of good luck (found)
Relevant feats:
Spell Focus, Transmutation
Greater Spell Focus, Transmutation
Heighten Spell
Lightning Reflexes
Transmutation was chosen because the most effective attack spell at 12th level is Baleful Polymorph. Heighten Spell, so I could increase the DC by one more by casting it at 6th level. Not that I would ever ruin a real character by doing these things, but I am trying to get the highest DC. Lightning Reflexes was chosen because it shores up the druid's weakest save. Note that the Wisdom score is pretty extreme, but it is accurate for the character in question at level 12.
Nastiest DC is for Heightened (to 6th) Baleful Polymorph: 10 + 6 (level) + 10 (wis) + 2 (GSF) = 28
Fortitude Save: 8 + 6 (con) + 4 (cloak) + 1 (stone) = 19
Reflex Save : 4 + 4 (dex) + 4 (cloak) +2 (feat) + 1 (stone) = 15
Will Save: 8 + 10 (wis) + 4 (cloak) + 1 (stone) = 23
So, I save versus my own nastiest spell on a 9 (60%). Is it the intent that the best a caster can do by sacrificing the maximum number of feats to increasing DC is affect the opponent 40% of the time?
Now, in reality, any spell focus feats would be spent on Evocation, and I would be using Flame Strikes. I would not waste a feat on Heighten spell, so the actual spells would be DC 26 Flame Strikes. Now I need an 11 to save (50%) which is still quite nice. Especially since I am rarely to be found in a combat situation without a number of protections from elemental spells in effect. If you add 2 more to the DC by reverting Spell Focus and Greater Spell Focus to 3.0 versions, I still save 40% of the time, which is very reasonable for my worst save. And this is against some idiot with 30 wisdom at 12th level.
So, yes, I think Spell Focus and Greater Spell Focus are too weak in 3.5, and will use the 3.0 versions.
Question: Is anybody going to use 3.5 as written? Everybody I have spoken to so far is planning to use a mix of 3.0 and 3.5.
Oh, and this may be stating the obvious, but Lightning Reflexes is a nice feat for clerical types. Iron Will is excellent for fighters, who have good Fortitude saves and enough hit points to weather a couple of failed Reflex saves, but really don't want to fail against, say, Hold Person. As for rogues, they have it rough. Their weaknesses are Fortitude saves (typically save or die kind of things) and Will saves (typically save or be rendered useless until I come over and kill you kind of things). Wizard types are the next worst off.