One of the chief complaints I've heard from vagina-owners about couples' vibrators is that because one arm extends into the vagina, things can feel a little, well, stuffed, when you add a penis into the mix. I have definitely experienced this with couples' vibe and, guys, it is not a great feeling. That's why I really like how tiny and delicate TIANI 2's arms are. They are much smaller than those on other comparable couples' vibes and, at least for me, their slimmer size made a huge difference. The toy also comes with two different arms, which should help more people find a comfortable fit.
Finally, when it comes to getting this thing in: Penis goes in first. This goes against what most instructions for using couples' toys recommend, but it made a world of difference for me, especially with TIANI 2's tiny arm. I just slipped it in from the front and it was no trouble at all. Also: Use lube. Obviously.