I've had several FWBs.
In contrast to most here, for me, I do lots of "dating" type things with my FWBs, and regular phone calls, texting etc, because they have all been friends first and foremost, so I naturally hang out with them and do fun things, as we did as friends, and the sex just came later. And yes, I don't really do presents, but we take each other out for dinner for our birthdays, buy little celebratory gifts for a promotion etc, as I would for any of my friends. The FWB relationships have lasted 18-24 months, on average, before it either fizzles or has turned into a proper relationship.
The difference for me is purely that there's no expectation of commitment, nor of exclusivity, although obviously I expect them to tell me if they sleep with anyone else because of health concerns, or if they start dating anyone else seriously because I'd want to be sure no one was being deceived or lied to.
I have had FWBs turn into relationships, when we both wanted it, and that was also fine - we just discussed it and then agreed. I did have a couple where they wanted the relationship and I didn't, and I ended up stopping sleeping with them, but continuing as platonic friends, to remove the confusing factor from the relationship, and not cause them to get hurt from unmet expectations/hopes.
I haven't found it causes any angst, but I'm naturally not an insecure or jealous person, so it doesn't bother me that they may be also interacting with others - I think whether it can work for you will depend a lot on your personality, sense of self, type of attachment and similar types of factors, which you'll know best.
Wouldn't call it blissful either though - it's the enjoyment of hanging out with a good friend, with added cuddles, intimacy and sex, so can be lovely, but maybe not quite to the extent of "blissful", because there's an awareness that there's an edge to the relationship beyond which it doesn't usually go (unless it turns into a full on relationship).
It can be a bit awkward sometimes if there's an FWB but you are also potentially looking elsewhere for a relationship - managing & communicating around that ethically and well can be a little difficult as it's not necessarily most people's "normal".
What most people here describe as FWB, I would call fuck buddies, which isn't a thing I do. That would be a pure booty call, and minimal other conversation/interaction/hanging out other than the sex. Wouldn't work for me at all, but each to their own.