I have a 5th level warforged warmage in a PBP.
What I find is that...so far at least...I'm doing okay overall. My damage output is really too great yet, since it's hard using ranged touches once the melee guys close in, and there's not too many area spells until 3rd level spells are gained.
I do see some future issues though. I'm going to be absurdedly vulnerable to enemy magic, for one thing. Mundane attacks won't matter so much, since my AC will be pretty decent, and I'll have good HP for a mage. But I'll need to dig up something to give basic energy resistances pronto, or risk being wiped by empowered Magic Missiles and/or Scorching Rays.
In hindsight, I think a sorceror would have been a better choice...though the thematics of a warmage are perfect for the character concept. Even with the Advanced Learning though (which I plan to buy a Repair spell with), it's going to be tough.
The crucial point is that you'll always have a TON of possible spells to cast for attacking...but you can only ever cast one, maybe two tops, per round. It doesn't matter if you have a huge list of them to pick from, because the fact is that most spell levels only have one or two "workhorse" attack spells, and the rest are all basically niche spells, useful only in fairly specific circumstances.
I mean, really. Who casts Ice Knife over Scorching Ray? Or Acid Arrow over the same? Most attack sorcerors do just fine with Glitterdust and Scorching Ray for 2nd level. If lots of fire resistant foes come up, then get an Extra Spell with a feat, or Energy Substitution. Same thing with Fireball and Lightning Bolt at 3rd. Orb of Force at 4rth.
That's ultimately the failing of the warmage. Massive redundancy. Beguilers avoid that, because their spell lists are innately better picked. They have a pretty good selection of spells, not just enchantments and illusions. The perks of a warmage are also not as good as a Beguiler (DC bonus and SR penetration vs a little extra damage and increasing ability to cast spells in armor).
In summary...sorceror or battle sorceror is probably a better bet than Warmage in most circumstances. Warlock would also be a good substitute for a Warmage except for the loss in area effects.