My own quick take:
Shield Changes: Fighter/Mage is no longer a high AC combination because of this change. The fighter/mage will generally have a comparable AC to a defensively oriented fighter if he has time to prepare (alter self) but will have a much lower AC in general. This means that he needs to get his defense elsewhere and be a more efficient damage-dealer.
Animal Buff changes: Fighter/mage's shouldn't bother with them anymore except as the prerequisites for item creation (which they now must make use of). The short duration means they must be cast during combat. . . and the fighter/mage will get more milage out of casting a scorching ray or magic missile spell with that standard action.
Power Attack changes: True Strike+two handed Power Attack is now an advantageous combo when the character has trouble hitting rather than just when it's almost impossible to hit normally.
False Life: Being core adds to the fighter/mage's hit points.
Ray of Enfeeblement: Now an excellent choice--especially in combination with the improved Trip feat. Also a very good spell of the Spellsword Channel.
Touch of Idiocy: Very good for the spellsword channel.
Enlarge Person: See Ray of Enfeeblement. Also good for armor-wearing fighter/wizards who want large size but still want to wear armor. Just be careful about the dex decrease. This is something that combat reflex based characters will need to account for since the reduced dexterity reduces the utility of combat reflexes, somewhat making up for the increase in reach granted by the size increase.
Haste: As a party buff spell, this is not (IMO) on the fighter/wizard's spell list any more unless he's more into helping the rest of his party than fighting himself. The use of the old haste was to enable him to finish buffing quickly (haste+shield/Greater Invis during round 1 then partial charge+attack in round 2 for instance) and to help boost his AC to stratospheric levels. The new haste doesn't do either.
Polymorph: Good for fighter/wizards who don't wear armor. Still, the duration makes it weaker than the 3.0 version.
Improved/Greater Invisibility: Imp Invis was good for short term scouting as well as combat. Gr. Ivis is just a combat spell.
Scorching Ray: A very good spell that takes advantage of the spellsword's higher attack bonus. Also very good for using in the spellsword channel (A fighter 2/Wizard 4/Spellsword 10 could have two empowered scorching rays channelled into his sword and unleash a quickened magic missile before his attack for a truly devastating single round attack--even better if he uses Arcane Strike on a 5th level spell for +5 to hit and +5d4 damage to every hit during the round (although that would pretty much tap the spellsword's high end magical ability out)).
Enervation: Very good for the high level spellsword channel.
Heroism/Greater Heroism: Very good spells. Fighter/wizards should pick these up at the first opportunity.
Magic Circle against alignment: Now a much more attractive spell since there are fewer other ways to boost AC. It's 10 min/level duration makes it much better than Prot Evil, etc for this purpose. And it also helps out your allies and hedges out summoned monsters (strictly side benefits but still well worth mentioning).
Tenser's Transformation: No longer useful to fighter/wizards. With Spellsword or Eldritch Knight levels, you won't be missing a whole lot of BAB anyway. And with the flat +6 to stats, you won't have a chance of improving upon your statboost items (especially since you now almost certainly have them). Is losing the ability to cast spells worth a minor BAB increase and some temp hit points. I don't think it is. (Especially when you could get the temp hit points with an empowered False Life or Maximized Vampiric Touch for the same or lower slot--and, in the case of False Life, without having to spend a combat action to benefit).
Greater Magic Weapon: By clvl 8, it's still worth it for an Eldritch Knight who relies upon multiple weapon (glaive, guisarm, flail, sword, etc as the need arises) and can't afford to have them all magically enhanced the way he'd like (although since a Spellsword gains fewer caster levels, it may never be worth it for him now).
Protection from Arrows: Even more campaign dependent. In most campaigns, it's now useless past 5th level or so since nearly all foes will have magic bows by then (although its greater duration makes it more useful before then). Before, it didn't quite keep pace with Greater Magic Weapon which made it useless against main-villain archers or archers with main-villain GMWs cast. Now, it's useless against anyone with a magic bow.
Rashak Mani said:
As well as picking on prestige classes... I wonder how the changes in spells have affected the potential of the Fighter/Mage combination ?
My first take is the +4 AC Shield Spell vs the old +7 AC spell. Certainly bodes badly for wannabe warriors. The Haste not giving an extra action also seems to limit the use of multiple spells followed by multiple attacks.
Enlarge is nice... short duration of Bull Str is bad...
ALSO -> What spells work very well for the SpellSword ? Especially lower level ones... scorching ray ? MM ?