Too weak.
I never even thought the old spell focus was worth it. The new one is next to worthless.
And as far as Spell focus somehow being better than the save increasing feats - get real. It would be one thing if spell focus increased all your save dcs. But it doesn't. Only for one school. And saving throws apply to alot of things other than just magic. You people need to remember that too.
And while a character can boost his spellcasting stat pretty easy with items and levels, it isn't exactly hard to boost your save DCs. One cloak of resistance +5 will give you a save bonus that it will take a spellcaster 10 points in his primary attribute to match. And while you need to boost three attributes to improve all your saving throws, consider this: three +2 stat boosting items is far cheaper than a single +6 booster item, and gives you all around coverage.
And unlike save dcs, saving throws improve as your level goes up. By level 20, even a weak save gets a +6 bonus, which isn't too shabby.
Let's compare some things at 20th level.
Let's say your spellcaster started with a 16 in his primary attribute (which is 1 above average). Let's also assume he put all his level up points into it, giving him a 21. With a +6 stat boosting item, he can have a 27 (for a +8 bonus).
Let's also assume he took spell focus. This makes his save DCs for his favorite school 19 + spell level.
Ok, now for our saving throw man. His strongest save will be 12 and his weakest save will be 6 (assuming no multiclassing or monks). We'll assume he has a 14 in those attributes (not too hard to do by level 20). This brings his base save up to 8. Now, with a +5 cloak of resistence, he has a 13 (A +5 cloak of resistance is only 25,000 gold, BTW, and improves ALL saving throws). With a +2 stat boosting item he has a 14.
Now remember, it appears that he is way behind, but you add a D20 to this. The average he will roll is 10-11, allowing him to resist the mage's favorite spells of 6th and 7th level, on an AVERAGE roll, with his WEAKEST saving throw. On his good save, the mage may as well pack up and go home.
Now, you could say that I could power up the mage more, have him start with an 18 attribute, give him spellcasting prodigy, and a +5 inherant bonus from wishing, but that would make a total of a 5 point difference and is about as extreme "munchkin" a mage can get in 3.5 edition.
But I didn't make my saving throw character anywhere near as good as I could have either. I could give him much better stat boosting items, give him inherant bonuses (or assumed his attributes were higher, etc), make him a Paladin or Monk, etc.
All in all, after getting rid of the Red Wizard and Arch Mage save DC monstrosities, saving throws are balanced if not ahead of spellcasting much of the time. Spell Focus' +1 is simply not a significant enough of a boost to make much of a difference, especially considering that it only applies to 1/8th of a Wizard's spells.