Okay they have of course more tricks than just one but still compared to the Wizard you'll have very few choices, and even compared to a Bard and Sorcerer your selection of options is somewhat small-ish.
As far as comparing spell selection between Warlock and Wizard then yes I agree Warlocks have fewer options. There is more to the game though than spell mechanics. For me the fun with Warlock lies in the RP aspects. Having a MC whose source of power is either taboo, or the result of some mysterious entity, allows for a lot of fun with the imagination.
I like playing most classes as they all have their strengths and unique attributes.
