From my point of view, these bars are great for finger tapping.
They are really intuitive.
It is true that when the device gets slow due to being loading the webpages the bars can appear with delay really messing around.

The preferences panel is great.
And I like the idea of the Add-ons in the N900. I use them a lot in the laptop.

Awesome bar... I would not call it awesome, but it is cool!

Of course not better than MicroB but neither worse...
Just different!