I'm playing a Dwarven Barbarian in one of my games. 4th level now...went berserker.
As CapnZapp mentioned...DR from rage + Reckless Attack = all kinds of win. Add on top of the Great Weapon Master, and it gets even better (kill or crit? Why thank you...I get a free attack now!). Add in the -5/+10 for the attack/damage with reckless attack, and you are dealing all kinds of nasty damage.
Frenzy is a problem, but it isn't as bad as you think if you manage it carefully. I *never* frenzy more than 3 times in an adventuring day. But if you need that extra hit against a big bad, it is extremely useful.
[SBLOCK] As a point of reference...we are playing HotDQ. Near the beginning, in the cave with the dragon eggs, you have a chance to meet a roper. I pulled my character in, so I went full ragey and started doing reckless attacks. I single handedly took out the roper in 3 rounds, frenzying each time...I was exhausted, but it was the last encounter in the caves, so it was worth it. [/SBLOCK]