It's like you have less privacy, but you may not care.
     It's like he's around whether you like it or not, but you may not care.
     It's like, if you're a really needy person, that's why you have him around... He's probably needy too.
     It's like you often have someone to needily hug while watching TV on the couch... and you share a pint of ice cream instead of having it all to yourself... that is if you're the type to devour a whole pint of ice cream.
     It's like you have expectations of him and you can get really sad or mad when those expectations fall short.

What's it NOT like?
     It's a lot not like when you are are secure in a relationship... then you wouldn't be "boyfriends," then you'd be in a "healthy r e l a t i o n s h i p." -- Hey, I'm just quoting the "experts!
     It's not like you're in a "healthy" relationship... but you sure as hell are in a relationship. ... In fact, you sure as hell are in a typical relationship... which makes that the norm... meaning, that would sure as hell be N O R M A L.
     So a "Boyfriend" relationship is not a "healthy relationship," but it is a relationship and a normal relationship. It's about as healthy to be in a relationship as it is to not be in one.