@Berit
Party Rose was actually the first of the Party variants I unlocked and I still enjoy playing her for her soundtrack during Party Time. Many players have said they don't like her as much because your default damage is a little less to balance out the damage boost you get while in Party Time but for me she's very fun and her speed boost and soundtrack make her very fun to play in my opinion and that counts for a lot.
@Screion
I initially found the Fire Rose awkward, it wasn't until I unlocked her Homing Upgrade that her full Charged Shot became a real force to be reckoned with, and it gets easier to make vanquishes with her at that point. Generally when I use her I try to lead with the full charged blast and then follow up with the little bursts- a lot of being successful with her, and really any Charged Shot variant, depends on learning when to pause for that build up and when to just plug away rapidly. I only use her in Multiplayer though because your finger will definitely get tired during the more intense Garden Ops sessions.
@pandareno1999
Personally I find that success with any Rose depends a lot on finding that right range and position on the map which allows you to fire Homing shots on the Zombies without being initially observed while being reasonably close to teammates for backup and getting a good feel for when you're taking too much return fire and using Arcane Enigma to beat a retreat so you can keep your streak going. Once you get that Homing Upgrade it gets really easy to terrorize novice Zombie players, but you have to watch out for the experienced guys which is why I like to save my Arcane Enigma for retreats only; preferably to lead the pursuer back into other Plant players for a tag team moment.