Of course it is, but in this case it does tend to need to be an informed opinion since we are talking about an electronic product.
You know, cite some examples of something working well or not well.

And here's where you let me down. Cite some examples of the browser "not working well". No need to cite anything for the mail client since there have been NUMEROUS well-founded gripes about that serious POS.
But the browser? On the latest firmware with the microb installed? Microb is still in alpha testing so of course it's optimized yet, but the Opera browser - now with Flash 9 support - is still the best in it's class on a handheld device.
I only use Microb when I need access to specific Google-based applications.
And again, it all depends on the sites you visit. A Flash-and-Javascript heavy site will load slower in ALL browsers, and seem to bog down a mobile browser expecially. That's just bad web design and not a fault of the browser. I bet if you turned Flash and Javascript off those sites would load a LOT quicker.
And I'll even cite two examples for you: Engadget and The Inquirer.
Engadget loads up around 90 "objects" on their main page.
The Enquirer loads up around 20.
Guess which one loads faster? That's right, that horrible-yet-entertaining rag called The Enquirer. Loads up in about less than 5 seconds on average, depending upon network connection. Engadget takes about 10 seconds on average to load.
Sad thing is, Engadget's tons-of-objects aren't that useful, mainly ads and links to other blogs from their parent company. I'm sure someone really taking the time to customize Privoxy and running a custom CSS template could speed things up for certain websites even faster.
And running Privoxy does tend to speed up sites for my by not even bothering to snag a ton of ads on every page I visit.
A little tweaking goes a long way towards improving the user experience.
Take some time out and try it sometime.