I think the keyboard is quite a subjective issue, whether it's going to be "good enough" for you, or frustratingly limited. Increasing the on-board flash to 2GB is a good move, that would at least have compensated for losing one SD slot.
Lack of a CF slot is not a big issue since less and less things use them - I only use mine for wifi or bluetooth and very rarely a GSM/GPRS card, and since both my mobile phones are bluetooth I wouldn't now miss the use of the use of the latter.
The N770 was quite a daring move into a niche market, the 800 fixed many of its flaws to become close to many handheld-linuxer's ideal. The N800 , to my mind, had two real flaws - a faulty design of the video interface restricting bandwidth and not having USB host mode. I guess many of us hoped that the N810 (or N900 as many hoped it would be) would put the icing on the cake with the rumoured keyboard and possible GPS.
I think the N810 has taken a step back towards the limitations of the 770, without giving us enough back! So, yes, I am somewhat disappointed, as details have emerged I've gone from "almost definitely buy" to "wait till the 820 or 900"!