I can't think of any others to share as my experience with the phone is quite similar to the other E51 users here.
Well, except for mine is the
first to be sent in to Nokia Care for a service...
I was told that my phone circuit board is faulty and that's the root of the problem. Pretty lame...
Anyway, I would say it's user interface is responsive and easy to navigate.
Impressive features and functionality to cater most of your needs for business and some entertainment.
Namely, 3G, HSPDA, WiFi, VOIP, PDF and document viewers, Music & Video players etc.
The main reason I get the phone is because it's the cheapest WiFi phone I can find during my time of purchase.
In short, I think it's a really worthy buy for it's price tag and long list of features and functionality though it might not be the perfect phone for everyone but I think it's far more than enough for me.
Just a side note :
I've not been using a handphone ever since I lost my previous phone quite some time ago because I can't find a good replacement for it.
Once I get the E51, it's really a welcome sight for me as the interface is easy and straight forward.
Therefore, I've no problem at all navigating/figuring out most of the features/functions without the need of digging through the manuals.

*typo*
agreed with what u said... i bought it because it was the cheapest WLAN phone as well..
circuit board faulty? sounds really fishy to me... how long will the repairs take?