Brave brave Sir Robin, brave Sir Robin run away. That sweet MONTY PYTHONS verse comes in mind whenever a SONATA ARCTICA album falls in my hands.  Now this is a band that has a really good taste in style. Their pop metal (no they DO NOT play power metal) is so shamelessly mainstream that you really can't blame them for being false. In fact when mastermind singer Tony Kako mentions that he never was into metal until lately and his main influences come from abroad then expectations towards heaviness luck reasonable ground.
Yet is melody what we look out for in a SONATA ARCTICA album and Unia is full of this. Though the album kicks in with the mediocre In Black And White the next tune Paid In Full set the whole listening on fire. The mid tempo For The Sake Of Revenge is equally good while as the road goes on several really good tunes pop up. Yeah Unia is definitely NOT the best album of SONATA ARCTICA (the spot is still occupied by the band's debut release Ecliptica) but still is an album that shows a mature band that knows exactly what they look out for. Some short experimentations and theatrical references can't work as evolutionary steps. No there's no reason doing so when you are a leading act in your field I guess.
So though this can be considered a stereotyped album still the professionalism of this band gives it this extra push it requires to avoid sterile copy / paste situations. My suggestion towards SONATA ARCTICA: include less fillers in your albums and write more tunes like Paid In Full in order to entertain your fans. Until then...