I'm never really tempted by these offers because I actually enjoy levelling, but this one comes with an extra perk: Every boosted character gets to choose one of five painted owlbear mounts for themselves (picture from the official news post):
Seriously, who wouldn't love to own one of these? I especially like the purple one.
Of course, then I checked the actual price of a boosted character on the Zen market, and it's 5,000 Zen. Even if you buy the biggest bundle to get the most bang for your buck, that's still about thirty quid. No owlbear is worth that to me.