This game is so fun! I was able to complete the Unit-Pedia over the course of a day, and it really forces you all sorts of interesting strategies, so I would recommend anyone to try.
Of course, I also got to know the strong and weak units, in the context of creating every Tier 3. I would say that the Adventurer and Bard are best for staying ahead of the curve, while the Archer and Mage have good damage, and the Warrior provides sturdy cover for ranged units. On the other hand, the Recruit (usually), and the Lancer seemed weak, and I would pass them up when going for the other Tier 3's.
Some of the specific Tier 2 paths also felt lacking. The Hoarder, Shop Keep, and Blacksmith are a bit too hard to use (mostly because I always need to be rerolling to find enough units for Tier 3), and the Entropy Mage never really did much until I already had a Tier 3 defensive wall. My personal favorites were the Hiker, Fire Mage, Scholar, and Weapon Smith, which worked well in lots of different armies.
Overall, it was really satisfying to go from struggling to make any Tier 3's to getting three in a single army – there is definitely a focus on skill, and minimizing luck instead of being bent to its will.
The luckiest thing I had happen was a One Man Army in turn one – that's a shop with only Recruits, and it happened to me twice! 