Bealcain, so right about the personality bit and a lot of sleep patterns are actually due to nature. I assume you did not have the same problem with ds1.
But one thing you can take comfort in is that your ds2's sleep WILL get better. To add to knifewieldingtoddler's post (to which I agree BTW), a newborn baby sleeps lightly for survival. But as it matures, it will have longer and longer periods of deep sleep and shorter periods of light sleep (from which it is easily aroused by hunger, cold, noise etc) and also take faster to fall from light to deep sleep.
I have 2 of the worst sleepers in the entire world - I mean it, dd and ds can wake 3 times an hour. Or it can take us hours to get them back to sleep only, crying and all, only for them to wake up 30 minutes later (repeat)! Both bf and co-sleeping babies.
And they weren't even hungry - if I put them on the boob, they would just comfort nibble all night long and not draw milk - it would do my head in.
With dd, I weaned her cold turkey during a nursing strike at 17 months. She started sleeping through soon after. You could have blown me over - I never expected that. I can't say with ds because he is only 1 year old but will wean him around the same time.
Apart from their sleep patterns maturing, once a baby gets past, say, one year, they are not frightened creatures in the night anymore. And when they cry, it could be because they are upset they cannot get their way (like being allowed to nurse). I know that I cannot wean ds without him crying. I can be there cuddling him and all, but he will still cry because he is not given what he wants. Once they are toddlers, I don't think of it as controlled crying but more like setting limits.
Dd sleeps through like a dream now, through all her brother's histrionics at night.