1. Fun/range gun : 8 or 9
Shooting this pistol is sort of like shooting a rifle in .22 WMR. That's not just because the end result is similar. It's relatively loud but has relatively little recoil. It's a lot of fun against typical plinking targets, like plastic bottles or overripe fruit. I've always felt that higher capacity adds to the fun so it's a win in that respect.
Negatives could include cost of the gun and cost or relative rarity of ammo. (It's no worse than .327 or .41 magnum.) This category is also highly dependent on if the gun fits your hand or if you like the controls. It also has to compete with a whole bunch of other things in the "for fun" category. (For these kinds of prices, you could get into a super-magnum like the .460 or .500 S&W.)
2. Duty gun : 7
It shoots well and is fairly easy to shoot well. The size is mitigated by the implication of open-carrying on a sturdy belt in this category. There, it's relatively light and neatly efficient with its twenty rounds.
I suppose the argument about armor would be more relevant depending on the type of duty. Of course, the type of duty will also affect your ammo choices. I don't know if the original armor-piercing ammo is available or under what circumstances. I don't know how well the different commercial offerings penetrate what kinds of barriers. Being that this firearm was designed for a particular kind of ammo and that it has been offered to the public without access to that ammo will always put the Five-seven in a strange position.
Cost is a factor here too. It will be across the board but there could be an additional hurdle here if your department, agency, or company is staring down the financial barrel.
3. Concealed carry : 3
Size is an obvious enemy here. It would probably be alright in most of the set-ups people use to carry larger guns concealed, if those set-ups are available for the Five-seven. I haven't checked recently but I don't recall the holster market for this pistol being all that large.
This is more subjective but I'm part of another group of people who prefer DA or DA/SA for carry guns. Despite making a line of nice hammer-fired pistols, FN hasn't bothered offering an FNX in their special caliber. For that matter, does anyone else make other guns at all in 5.7x28?
4. Home defense : 5
It's good because, again, it's a twenty-round pistol with light recoil. People will bring up over-penetration but let's be fair. Most pistol or rifle rounds go through wall(s). Since rifles, carbines (including pistol-caliber carbines), and shotguns are competitors in this category, it stands out a lot less. Also, has anyone discharged one of these indoors? Just a guess but 9mm, especially in a carbine, would probably be kinder to your long-term hearing.
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