Don't choose NOT to level a mage just because others don't like it. I "tried" mages a few times over the years and was disgusted by the squishyness and all the downtime drinking water for mana. It was painful.
I could never get a mage past level 12-15 before I gave up.
Eventually I caved and forced myself to push it out with a BG pvp undead mage (my main is Alliance and I didn't want to get distracted by people I knew). It was super fun and really helped me to understand the mechanics of being a mage and the wonders of ranged combat.
Eventually I made another mage on Alliance side and I have never looked back and I can't even log on my old characters anymore without being bored in 5 mins.
The good...
Fire = Awesome to watch. Dotting up 3-4 targets with living bomb, putting down a flamestrike and watching all the explosive goodness is just plain satisfying.
Arcane = Chart topping DPS that makes a lot of people just say wow. The hit requirement is a lot lower in certain arcane specs making it easy for you to just pile on the damage and haste and increase your DPS even more.
Frost = So much control and survivability that once you master it, it is almost impossible to die in a PVE encounter. If you love to solo stuff, frost will make you giddy. The pet is fun too
The Bad...
Fire = A ton of damage comes with higher hit requirements to stay competative, so you need good gear before you really start seeing results. There is also a lot of "Why are you not arcane" crap thrown your way :lol .
Arcane = B-O-R-I-N-G spells....it's painful to watch but the DPS outways this for most. Not for me. Also while your DPS will be high, your overall damage can fall behind until you have the gear. There have been many occasions where I will be much higher in damage on my fire mage but well below an equally geared arcane mage in DPS meters.
Frost = Anti-Raid spec. Until the upcoming patch, you are a joke in serious raiding. This limmits you to heroics, pvp, etc. Some raids won't even take you as frost. Although in heroics you can do some serious AOE damage and fit in fine.
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Non-Spec related pluses....
- Teleporting : You will wonder how you ever got around without it. Painful to not have when playing other classes.
- Food : Making your own food and water sucks at first cause it just is not good enough, but eventually it is very nice to be self sustaining.
- Range : If you have not played a ranged class before, it is very satisfying to know that you are squishy but destroy things before they get to touch you.
Non-spec related negatives...
- Begging You will be constantly begged for food, and teleports to the point that even the nicest of people may get snippy ...hehe
- Mana : Reliance on mana is heavy depending on spec. Running out of mana sucks and until you learn the class you will run out, alot.
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Overall it really doesn't matter what spec you play as long as you have fun and IMO Mages are a ton of fun once you get used to the way the class works.
I love my mage....obviously. For the record my previous mains were Rogue, Druid, and a Pally.