I'd say the point at which (slightly more) casual players should jump in is when we get wireless (already in the next major Vive upgrade) and a significant reduction in screen-door effect.
I've already got wireless and it works perfectly. You can get the TPCast wireless adapter for 300 on Amazon. It makes the whole experience way better as you aren't constantly worrying about chords.
That said, I rarely use the Vive. Even wireless, it's still frustrating as it's on the cusp of being an awesome product, but there are still too many burdens with the interface. Once they make "gloved" controllers that allow you to move your fingers and upgrade the screen quality it will be a truly revolutionary product, but at the moment I think it's only worth the money if you have a lot of money to blow and are primarily interested in it as a novelty.
The absolute best game I've played with it is "Superhot: VR," which I'd say is a killer app. You quickly realize that VR games have to be short and designed to function within the size of a room to work very well, and Superhot is exactly that. And the "time only moving when you move" gimmick and general gunplay work very well in VR. I genuinely felt like I was in the Matrix at times, which was awesome. However, most other games I've played are pretty gimmicky and I haven't encountered anything that I would play seriously as a game, as opposed to just being a 20 minute diversion before uninstalling it. You absolutely will not be using a Vive to play games for hours at a time like you do with monitor based games. The experience just isn't designed for that. Long form games like "Skyrim" and "Fallout" are so maddeningly frustrating to put up with the interface bullshit that I could never imagine playing them for 40 hours straight. Also, I was never a person that's ever gotten motion sickness from anything, but any game where you move around will make you want to vomit after 20 minutes. And the alternative (teleporting around) feels really unnatural to me, which puts me off playing most games that weren't designed to be room scale--especially games that weren't originally designed for VR (Which isn't to say all conversions are terrible. "LA Noir" was really well done just because Rockstar basically cut out all the stuff that wouldn't work and redesigned the rest of the game's interface from the ground up. Payday 2 also works fairly well, as while there's movement, most of the game is centered around stopping at various points to fight off waves of enemies).
As to non-gaming uses, that's been a big disappointment too. I was super excited when I got the Vive to use movie theater apps to watch massive IMAX sized movies, but the video quality is still bad enough that I couldn't imagine watching a whole movie in it without getting a headache. A computer monitor looks 1,000 times better.
I don't mean to shit all over it. If you have the money, I think it's a unique enough experience to be worth getting. It just feels like 1st gen technology in every aspect. I'd say by 3rd gen, they will have most of the kinks worked out and at that point it will be massive.