I want to chime in that I.believe most Summoner(and psionics) hate is based off of people who cheated. Of course cheating characters look to good. They were cheating. As.time moves forward, more and more summoner(and psionic) players are implementing the rules correctly. It is hard for most haters to not constantly complain about what they saw when what they really saw was cheating but didn't even know it.
Summoners have mediocre hp/bab/weapons/spell casting with few per day. They also have mediocre saves with 2 poor categories and 1 strong attached to an ability of no special use to the class. Light armor and no shield means they have weak AC. The Summoner itself is rather fragile and not all that contributing.