The HD cap is caster level +1.
It's still a powerful spell, and the good thing is, that it scales with level, so it's still reasonably good at higher levels. But, I believe, it's fair enough with the errata. My sorceress is currently using
Summon Undead V via
Greater Shadow Conjuration at 14th level, and it doesn't feel overpowered in play, even though she can summon four quite nasty huge dire bear skeletons with it.
[SBLOCK]Advanced Dire Bear Skeleton
Huge Undead (Shadow Creature)
Hit Dice: 17d12 (110 x 60% = 66 hp)
Initiative: +5
Speed: 40 ft. (8 squares)
Armor Class: 12 (-2 size, +1 Dex, +3 natural), touch 9, flat-footed 11
Base Attack/Grapple: +8/+30
Attack: Claw +20 melee (2d6+14)
Full Attack: 2 claws +20 melee (2d6+14) and bite +15 melee (3d8+7)
Space/Reach: 15 ft./10 ft.
Special Attacks: -
Special Qualities: Damage reduction 5/bludgeoning, darkvision 60 ft., immunity to cold, undead traits
Saves: Fort +5, Ref +6, Will +10
Abilities: Str 39, Dex 13, Con -, Int -, Wis 10, Cha 1
Skills: -
Feats: Improved Initiative
Alignment: Neutral Evil[/SBLOCK]
Bye
Thanee