Yuno is a hottie and performs OK as a complementary piece but ultimately toggle skills are fundamentally weak on Healers because their stats and attack speed is balanced to meet much different benchmarks than the numbers good DPS units are aiming for. You basically need skill modifiers like Pippin's that rework your attack style from the ground up to be relevant as dps and even then many people would still rather have a nice long duration heal buff instead.

Overall, I'd put Yuno roughly in the same tier as Shiho--she has the advantages of better range and mild relevance as a stat stick but her non-skill healing output is lower due to the big speed difference and she's noticeably more expensive.