My previous campaign had a barbarian. At the end of the campaign he was:
Rusk: CG male human barbarian 13/fighter 6/champion of Gwyharwyf 9 (Exalted Deeds... I made Gwynharwyf a celestial vassal of Tempus in my FR campaign)
With dire charge, dev. crit., combat brute, and a +6 adamantine intelligent lightning blast greataxe, most enemies died with one full attack.
Of course, he couldn't fly, had very little defense against magic (a cloak of resistance +5 helped with saves), and he was an instant target. His spot and listen were also bad (compared to other's), so he was often falling victim to surprise rounds. His will saves were awful, so he often used instantaneous rage to try to beat fear effects (which he often failed anyway). He was played by a masterful player, so it was a joy to DM Rusk.
I will say that, even at his height, Rusk was only ever balked by two foes: a trio of glooms and an xixecal. The glooms, hiding from Rusk, almost killed him in one round with their human dread daggers before the spellcasters obliterated them, almost killing Rusk in the process. The xixecal was... well, beyond any of them. They annihilated its fiendish white dragon servants, but the ice colossus itself was pummeling Rusk with its slam attacks while the spellcasters whittled away at it. They had to retreat, eventually fleeing by the wizard's teleportation magic.
Rusk filled his niche perfectly, being the only front-line brawler in the group. He adventured with three others, each of them epic spellcasters (an elf wizard, a human cleric of Mystra, and a gnome arcane trickster), so he was often layered with spells before battle (when time permitted). I had no problem with him slaughtering foes. In fact, I went out of my way to set up dramatic, one-on-one duels for Rusk. Whether githyanki bounty hunters, astral stalker hunters, the odd upstart or "wannabe," or a balor gated in by Vlaakith herself, I tried to give Rusk those moments of glory.
I had a lot of fun with Rusk.