I still don't believe it's true. Having said that I'm sure someone mentioned about the maps in the original being more open than they are now (which they are). This, along with the plants more defensive abilities, helped keep the game balanced. So last night I played pretty much exclusively plants, and turf takeover (I'm assuming that's the gamemode most people are playing).
Great White North:
Plants won pretty much ALL the time. In one game we had around 6 chompers to counter all the super brain / all stars. On that occasion they didn't get past the third cap point.
Zomburbia:
Ugh. This is where the close confines of the spawn and exits to the first cap put plants at a major disadvantage. Plants didn't win any last night. I'm putting it down to both map design and very bad counter picks in the games I played (sunflowers as front line, cactus just trying to drone from spawn). I know from playing it, that once past the first 2 points it is much, much easier and the ending one is a piece of cake, getting there is a problem though. You'll need alot of corn, citron, peas and chompers to even attempt it.
Moon Base Z:
Seems pretty even so far. I'd say the hardest cap points are the 2nd/3rd. If you pass them you should win.
Seeds of Time:
Another fairly even map after the patch, BUT it would seem that if zombies can get past the 2nd cap point you will find it much harder to contain them. I've seen this go down to the last second a few times, completely unsure who was going to win. I'd say it favours zombies slightly.
Bar zomburbia it doesn't seem all that out of whack to me. I'd be quite worried that any buff to plants might just be the tipping point that puts them in front again. I think it would be better to alter zomburbia as this is the one that seems to be a major problem.
Personally I'd love to see Main Street again. That would be amazing.