Handled one. In a nutshell:
Horrible trigger Really? Fair enough, to each their own, though I found this one to have a crisp break with almost no overtravel, a pretty short reset, and probably a 6lbs ish trigger pull (just a guess, but I considered it pleasant)
Expensive and hard to find ammo Fair point. Ammo is pricey ish at ~$27usd/50rounds, but it is getting more common and readily available online in Canada
Replacement part might be an issue The FiveseveN's are still in production and in service with a bunch a ton of LEO. I could see parts 'not in stock' being the case, but would expect any FNH dealer to be able to get parts in for it
Not the best ergonomic/controls The controls are definitely different, notably the safety, but I thought it was actually really neat being able to actuate it with the index finger of my shooting hand (it's ambi). Oversized mag release was in the usual spot and is reversible if you're a lefty. And the takedown is on par if not easier than a beretta. Slide catch/release is a little small/low profile perhaps, but seemed to work fine for me. Personally I would consider myself a fan of it's ergs
If you are looking to collect, go for it. If you want a shooter, I'd pick something else. The FN Five Seven fall in the same category of the Desert Eagle.