Ok, here's my 0.02 €:

Generally, I'm not having any major issues with the device speed. However, there are some things that will make the device unacceptably unresponsive (try scp:ing in a lot of music files for example).

You're not specifying what format your music is in, or if the websites you have open are heavy. Some music formats on the device get played with DSP acceleration, while others (like Ogg Vorbis) unfortunately won't. For the websites, there are some that will even slow my dual-core laptop to a crawl.

Considering the mobility (dimensions, weight) of the device, I'm quite happy with the performance.

One thing that may cause major UI latency is swapping. When the device runs out of RAM, it moves some RAM content to disk (i.e. swaps). If something that the software suddenly needs is swapped out to disk, bringing it back in may cause large delays in operation.

Linux has a system variable called swappiness, which controls balance between keeping program code in RAM or using RAM as filesystem cache (google for 'swappiness' for more details). On the default settings, swappiness is set to 100 (which is the maximum) on N900. In my experience from desktop world, lower swappiness values may give better UI responsiveness when many applications are being used, but I really have not gotten around to play with this variable on the N900.

I agree with this point, there are some annoyances here. However it's nothing that a good firmware update couldn't fix ;-)

I'm a developer myself, so I'm comfortable with "world not being ready". While it's true that there are not that many apps currently available, I believe that the situation will get better over time.