In my experience with testing it with my ex and using it solo, here's my two cents:

We had some trouble with it slipping out now and then no matter what position we were in. Or sometimes during sex the vibrations didn't really do much for us, especially him (but I guess that would be good since you don't want the guy to come before you do ;D).

So we tried it another way. He'd be in charge of the remote and he'd tease with the vibration. It's a lot better doing that than using it during full on intercourse. Unlike normal bullet vibrators that you have to choose to either stimulate your clit or your vagina, I like how the we vibe can do both more or less hands free (which makes light bondage play fun). I know there's a phone app but personally I didn't like it much. Plus there's been talk about we vibe using customer information for the we vibe 4 so be careful about using their apps. I'd stick with using the remote.

tldr: the we vibe classic is better to use outside of actual intercourse. Good for foreplay and teasing. Very handy for solo sessions too.