Pros: Avoids the usual "Trinket Cooldown" when equipping, so you can simply place it on an action-bar and click it a few times whenever you happen to run into the water (just remember to swap-back afterwards).
Cons: Ahem...
- Not technically a "toy" like I expected it to be.
- Can't use it in combat (so no aquatic pursuit/escape), and you're pacified/silenced if the effect is already active.
- Effect is cancelled if you leave the water's surface (jumping/knockback/etc.).
- Effect is also cancelled if you encounter "invisible barriers" or "fatigue waters" (so it won't help you swim to Teldrassil).
- Even when you CAN use it, it's only a 35% swim-speed bonus (unlike a potion's 100% bonus), so you'll usually only "save" a second or two (which you'll then "lose" when you have to re-mount).
TL;DR - I'm
really glad to have it, but I doubt that I'll use it much.