Not only is this a great park and jib board because of its soft flex, it's also a great board for learning and progressing on. My local/favorite resort, Brighton, UT, actually uses this board for their rentals. The soft flex of the v-rocker and mellow sidecut help beginners feel more comfortable initiating turns and getting the feel of snowboarding overall. I took my dad and brother out for their first time ever with these boards. Both had never touched a board before or even been at a resort (they're from AL). My little brother took to it pretty fast and was lapping my dad all day (he's kind of old so we'll give him a break). I also demo'd the board during one of their much needed breaks.
My brother is 5'10, 160 lbs, size 10 boots, and rode the 151.
I am 5'6, 125 lbs, size 8 boots, and I also rode the same 151.
From watching and teaching my brother, I could see that this board was really easy to learn on. He's never been on a snowboard or even a skateboard I don't think. He learned pretty fast and was doing J-turns by the end of the day, almost linking them up.
From the couple runs I took on it, it had a pretty soft flex, easy to butter on and I thought it felt great in the park. It was definitely a little long for my liking in the park but I still could stomp some boxes and wall rides on it easily. Definitely felt like one of the softer boards I've ridden. I'd rate it a 3.5 for flex.