It needs to be longer, definitely. It hardly makes a difference due to the extremely short time in which it has any effect. It also might be a good idea to change its interaction with her E and make it give a speedbuff the entire time it's active that delays over time.

This sums it up nicely. I hadn't considered that synergy with the ult which would be awesome.

Maybe it will get attention in the next patch... clearly the majority find it too weak!

i wouldn't mind if it was stackable maybe but the 30 ms isn't noticeable until it saves your ass much like janna's passive.

only difference is that 30 is about 8-9% of your base ms rahter than janna's which is 3.

True, but Janna's is available with 100% uptime and 100% range, which is very different. And her percent based increase scales better, of course.

Although it is admittedly a skill and not a passive, I think Sona's Song of Celerity is a better comparison:

So she provides 2/3 of Nami's passive bonus automatically, all the time, in this stance.

Now on top of that, here is a nice, big, noticeable bonus with only a 7 second cooldown.

Again, Sona's is a skill, not a passive, so I realize Nami's should not be as strong. Still, the difference is kind of ridiculous.

She has 2 spells that can give MS, so increasing it to 2 secs really means a 4 secs MS buff if you use it on the same person. Not to mention her heal can bounce to multiple teammates & give them the buff as well.

I feel it's in a good spot.

You answered this yourself, Sona's is a skill, not a passive.
Also, Sona doesn't have a spammable AOE stun every 10 secs.

Every support should not have the exact abilites w/ diff particles & names..

The "passive" on Sona's skill is almost as good as Nami's passive, and then she gets a huge scaling boost on activation. It's not even close. Some champions get stronger passives (*cough* Darius) and some get weaker ones, but the bonus movement for Nami is really brief AND not really noticeable which doesn't seem quite right.

Right, again you are comparing abilities to passives.

her passive is fine imo reasonable spam of her abilities you can usually get someone to safety

Hemorrhage
Toxic Shot
Oops, I did it again. There is nothing wrong with comparing things as long as you acknowledge each kit should be considered as a whole. In the case of Nami, I think most people find that her kit is strong but not so strong as to warrant a passive that isn't even noticeable.