I started a gnome mage for fun...got him up to level 8 in 3 hours because someone was giving away pet toys in PoK when I was passing through after getting my level 4 spells. Did you know that you can get 20% normal experience for killing a red con mob in Paludal?
Although it was fun, since my main is a beastlord I'm much more of the "fight alongside the pet" school of thought, and it's hard to shed that. I do love being a pet class, though, so I thought I would enjoy playing a mage. I'm vaguely considering trying a necromancer out too...I do appreciate their versatility and mana regeneration abilities. From what I understand, that's the basis of a lot of the whining that mages have...the lack of self-cast mana regeneration compared to pretty much every other pure caster class. (Yes, they can mod rod, but it costs them more to cast than they get back from using. I think.) And I think they're the only pure caster class that don't get a simple root, snare, or fear spell...they have to use their pets as crowd control. It definitely seems like mages are becoming as rare as monks nowadays.
Anyway, back to the original question, definitely give it a few more levels before you decide to shelve your mage or not. There's only so much you can decide for yourself from 4 levels. In the end, if you're having fun playing it, then it's worth the effort for sure.
Game on,
The Oneiromancer