People are right when they say that it's important to consider what kinds of games you like, but there's more to it than that. I've had a PC-FX for a while now, and test driving a few more PC-FX games today, and I noticed a sad thing in general about most of what I've played so far.
Let's talk about budgets. This system apparently sold around 100,000 units before NEC discontinued it. This means that when any company made a PC-FX game, the business side of the production had to acknowledge that in all likelihood, they were only going to sell between 5,000 and 20,000 copies. Contrast this with the more popular systems, where selling 50,000 wasn't particularly difficult even in the Japanese market alone. Heavy hitters especially could count on selling hundreds of thousands of copies.
Unfortunately, this difference in scope of sales really affected how much money was put into PC-FX games. Frankly, even in the genres where the system supposedly does well, most games feel fairly low-budget. A few have a certain shine to them, but most of the system-exclusives look like they came from small development groups with very short schedules.
That's why ultimately, even the PC-FX's collection of RPGs, S-RPGs, love-simulations and miscellaneous gal-games don't hold up all that well against the best offerings from its rivals.
And so, even a person who enjoys the kinds of games that seem so abundant on the PC-FX still might not get much of a kick out of what is actually available. It's not like the PC-Engine, where there's a strong argument to be made for a lot of the shmups and RPGs being the best of their generation. With the PC-FX, it appears to be mostly average fare or worse. All in all, it's suited to NEC fans, collectors, and gal-game connoisseurs, but that's about it. To a general gamer, you might find a taste of some unique mid-90's gaming and anime, but if that's you, you've really got to ask yourself if that alone is worth the investment.