I've only had the 5800 two days but so far it has exceeded any expectations. The screen is superb, colours are vibrant and it is very responsive.
Movies look great, I loaded some films up to the 8Gb card it came with. Sound blows you away. Through the supplied headphones it is even better.
I've used it to connect to a couple of WLANs without too much fuss, one though said I needed to go through Orange GPRS (typo?) so I wasn't able to connect. I am sure it was the users fault

.
I have skype and msn working through a program called fring. Works superbly. As does the touch screen keyboard, qwerty does a great job too and is accurate when having the phone on its side.
The Xpress button gives you quick access to all of your media, you can change photos by sliding them like a slideshow.
I am still learning about it but very impressed so far.
I guess the only negative point is its size, it is slightly bulkier than my previous phone, SE W810i. But the size is soon forgotten with everything it gives you.
5 stars so far.
On another note, does anyone use a protective cover for the screen or a plastic/crystal back? I've seen lots on the bay but don't know which to get!!
Also, Orange had messed up my contract, someone hadn't put through what they offered me properly but they corrected it today (after 38mins on the phone).
£19.50 a (18) month. Dolphin 35 plan. Unlimited sms, 250mb of internet data.