This is really cool
I think it could use re-tuning (I'm sure that's already in the works), but I think this has a lot of solid concepts. Ranged zombies were always sorely under-used and the level design here really complemented their function. It's decently challenging, too. The plant rebalancing, I think, was for the better in most cases and costumes are a great idea. The bosses were unexpected and impressive (even if the pool boss got on my nerves).
I think night could use a re-examination, though. It's where most of my complaints lie. I was really woo'd by day time, so the sudden nose-dive in lawn variety was disappointing. Fume-shroom is when a lot of the strategy dies since graves pick up to compensate for its presence. You no longer have to destroy graves to kill and their damage isn't shabby, either. So they spawn everywhere; randomly, on your plants, on your valuables, out from suspiciously sturdy necromancers, each stone with more health than a buckethead.
A lot of lawn malfunctions came from this, too. I would notice a zombie managed to get farther than the potato mine I swore I had placed only to see a grave where I placed it. I'd end up having to dig up and rearrange my lawn with my limited sun to kill this one zombie that got by on chance. My luck may just be shit, but a lot of plants I placed to prepare for waves would be suddenly destroyed by graves. Like, it wasn't uncommon for me to place a wall-nut on a packed row only for it to be buried by a headstone seconds later without warning. Or somewhere I wanted to plant was sealed up by a grave the moment I took my eyes off it. Since zombies can't be pushed back once they advance in this game, they'd end up destroying my things and I'd be slapped with a loss that I felt wasn't my fault. This makes me think you want to keep me on my toes, but instants are few and not very strong in this game and the sun to use them doesn't exist on night levels. Dealing with surprises is a hassle.
As for lawn variety, all those plants you got in the day-time are ineffective for piercing graves or way too expensive to set up. I never ended up using bowling bulb. Fume-Shroom spam was the strat. Hard-mode night became very simple when I used it. It was mind-numbing. I really wanted to use the new Peashooter costume I was given, but it wasn't long for the night.
Those are the primary criticisms I wanted to get out there. I like the difficulty. PvZ is naturally designed to be easy and approachable, so veterans have to rely on fan content for interesting play. But I think night went about it the wrong way. I trust that other issues will be ironed out with time. Serious Watermelon is cool. Bye.