Disappointed?!
Summons are some of the strongest spells in the game.
Each summon is useful - even the Rabid Dog will take a punch from a Dragon, or will soak a spell from a Lich. Having your summons taking the damage instead of you is
good.
The Spiders from the Spider Spawn spell are powerful.
They are immune to Web (Spiders + Web will make any low-mid level fight too easy), and have Poisonous attacks, many times per round. The poison bypasses through Stoneskins, and kills Trolls.
The Skeleton Warriors from the Animate Dead spell (after level 15) are amazingly powerful. They can even be your main summon in ToB - just ask Dundee.
90% MR, Low THAC0, "Undeadish" Immunities, long Duration - you name it. [img]smile.gif[/img]
Perfect for fighting both Steel and Magic.
Invisible Stalkers enters the play invisible, making it good for fighting agaist Mages. He also has some minor immunities.
Mordekainen's Sword are just too mean for words to describe. They're
100% resistance to
all damage (slashing, fire, etc) except for pure magic damage, and are immune to mind affecting spells. The best tanks in the games,
maybe excluding the PC.
Don't even make me ramble about the Clone spells (Mislead, Project Image, Simulacrum) or Planetars (probably the best spell in the game overall, but it's a matter of style)...