My contribution was the Fast Healing / Regen exception, I remember.
Polar Ray has one single good use and that's killing large single fire-based critters like, say, red dragon end bosses. There's no save meaning they will always take full (i.e. double) damage and they are easy to hit with their pathetic touch AC. Watch them cry as their huge save bonuses avails them to naught.
But outside that single very specific case, it
is an underpowered spell. I think the game needs this spell (i.e. a highish level damaging ray), but not necessarily at 8th level. Or, possibly adding a minor effect, such as a fort save to avoid being slowed for 1 rd / lvl would be cool.
I wouldn't have had a problem with that. The problem with 3.0 buff spell has never been that you'd cast a whole bunch of spells every morning that lasted all day long, though the bookkeeping could become a nightmare (it took me easily 30 minutes to write down all the spell effects on everyone in the party and then explain it to the DM with my 15th level 3.0 cleric). Rather, the problem is that you could do all that spellcasting the day before, with extend spell and bead of karma, and get super good buffs that lasted at least through the next day, and had all your spell slots available for use at the same time. And, of course, multi-empowering got out of hand fast (I once rolled a +10 to my Con with Endurance. Hello 75 more hp for that day

)
This is why I have no problem with 10m/lvl (essentially, this will last through a whole day's adventuring), but 1 hour per lvl is too much.