Gah, yes, I've yet to beat it after probably at least a dozen attempts. Most of the games I've started with basically no useful inexpensive plants so I'm playing a defensive game as the AI creates large and deadly zombies (Hot Dog Imp 5/5 strike-through with deadly from the Toxic Waste Imp sitting in the water (which I can't do anything about with no trick that does damage nor any water plants) or a boosted Vimpire that therefore kills 2 small plants in that lane and becomes 8/8 Frenzy Deadly!)
Much of these games I've not even got a 2nd Super Block superpower trick as I've been killed with a few quite large attacks... Many I've started with 4 cards costing 6 or more and at least once even after swapping out all 4 starts I had no cards that cost less than 4! So except for the starter superpower trick I was unable to do anything until waiting until (at least) my 2nd turn.
By the time I am getting any traction I'm down to just a few health and then it's over.
I especially feel cheated since there's no way to effect the outcome, no changes to the deck that I can make; no way to spend a bit of gems or what not to skew the odds a bit like many games (Angry Birds Blast for example allows you to buy boosters for each round, etc.) so I'm just stuck with dumb luck.