I built the non-upgraded deck saturday and started grinding gods....Only won an upgrade or two, other rare cards that I got, I sold so I could pay to upgrade cards....I'm at about 8 upgraded cards right now (like 3 pillars, 3 hourglasses, supernova) and it's a touch easier.
some of the gods are damn near impossible to beat. Seism is a huge pain in the ass. I did get an EM win against him last night tho - got lucky and he was only able to drop a single tower first turn, and I got an armored Otyugh going before he dropped any creatures. One thing I'm finding though is the lack of life quanta...With the Sundials needed to stay alive sometimes, and to draw cards, having the quantum for Miracle can be rough. I'm sure once I upgrade more towers/Nova that will fix itself, but right now, it's a pain. I'm considering adding a second Fire Storm (or whatever it's called) to clear the way - as some of the god decks - if they get an early start, you can't recover fast enough.
Otherwise, I'd say I've won 25% of my games so far with the mostly non-upgraded deck...Slowly going up with upgrades.
Thanks!