The issue that the dissent fixed on is the one that might also be the political chain around this measure's neck: the very restrictive requirements for signing petitions to require a referendum for a particular plan amendment. The dissenting justices found that the summary's failure to disclose those restrictions made it misleading. I'm quite sure that quotes from the dissent will be placed front and center in materials attacking the amendment.
I personally wish those provisions were not there - or less onerous. I think that the idea of having a referendum by petition (rather requiring them automatically) is a decent compromise - but the pretty extreme limitations on this amendment may limit its use as an anti-Hometown Demagogy weapon.