This spell came up in the epic game I'm in. Two people had it, the eldritch-knight type PC who was polymorphed, casting Wraithstrike, power attacking for 16 (his BAB) with a two handed weapon, and blowing 4th level spells into arcane strike against big opponents w/ low touch ACs to land 5 attacks (4 iterative+haste) in the 60-70 range every hit. The second was a juvinile gold dragon NPC (CR 10!) with a single sorcerer level, who had it as his only 2nd level spell, able to cast five times a day.
The epic character was doing epic damage. It was high damage, but it burned through resources quickly, and while nasty wasn't out of line for alpha strikes from other Epic characters. On the other hand, a CR ~11 dragon with it would probably clean the clock of an 11th level party if it could do a power attacking full strike with it. (Note: In this campaign Power Attack had been house-ruled down some, to mimic Str, so it was only *1.5 on two handed weapons.)
Basically, the spell doesn't seem to be a problem at all except in conjunction with big damage adds from elsewhere. Power attack is the most obvious - making it easier to hit directly adds to how much BAB you can switch over for damage. But I can see an two-weapon arcane rogue (daggerspell mage?) dropping one of these to make sure all of his sneak attacks hit, which means just removing STR and STR feats isn't the solution.
Cheers,
Blue