We co-slept full time for the first 6 months, then art time for another 6 months. Mostly it was all 3 of us in 1 bed. But maybe once every couple of weeks DH would sleep in the spare room for a couple of nights. This was usually during teething or when he had a huge workload which required him to get up very early (4 am) and it was so that he could get a decent night's sleep and also so he wouldn't wake us up when getting ready for work.
I always missed him and didn't like sleeping apart. I never resented him for sleeping while I was up with DD. Due to his snoring, we actually slept better when he wasn't around - lol.
I personally wouldn't want to make it a regular occurence. I find the responsibilities of parenting are hard enough on a relationship without feeling like the baby separates you. On the other hand, loving a child together is incredibly strengthening for the relationship, too.
Other people might not associate those feelings with sleeping apart and it might be a good solution for them. So I guess every situation and every couple is different.

Saša