Is There Something Unsuitable About This Power Supply?

Depends on what use you have for it- perfectly suited to some uses,not at all for others.

other than the fact it only goes to 13.5v? ...good as a converter, but not as a charger.

that's the nes-350-12... an nes-350-15 is $48 on ebay (higher voltage, lower amps)

when it comes to mean well power supplies, the dash 15 series are generally adjustable from 13.5v to 16.5-18v

for more amps, move up to the 450 series for about $65