Aye, I second the slow start. The first few hours outside of the vault are quite slow, so to speak, and even the early exploring is a tad uneventful due to your limitations in skills, weapons, and ammo, meaning you dare not venture too far, and the game not throwing too many of the more "interesting" enemies your way. Although the latter could be decided by your choice of exploration direction, I suppose. But the slow start is far from dull! I've enjoyed every moment of the game thus far. And it depends on how many hours equate "early" playtime for each individual.
I feel it is well balanced, and like most things, the game starts out slow, gathering speed as it goes, becoming more interesting at every turn. And to be honest I don't think it's noticable when playing. It only becomes apparent in hindsight, when thinking back and looking at it in comparison to what came after. I was so caught up in the back story, the world, the environment, the soon-to-be-experienced solitude, the choices to be made, etc, that I don't recall being left wanting.
I'm about 30 hours in now, and I'm level 8. I've still to talk to Colin Moriarty about Dad, or else hack his terminal and save 100 caps at the cost of some karma. I haven't decided, yet. I just went out to explore and do side-quests and I've been caught up in it all ever since. Although I'm now considering chalking off Moriarty's part in the grand scheme of things.
I was fighting a group of raiders earlier, at some armored bunker, and there were brotherhood of steel outcasts nearby who decided to join the battle. One of them died in the ensuing scuffle, and I looted his power armor, power helmet, and super sledge. Great success! Although I can't use the damn armor without power training, as it turns out! Doh!