S60 is ok, maemo could be much better
I've been using an N78 for almost a year and can't complain, it does what I want (til now) in a phone, s60 shows its age but works great with the base software + a few 3rd party apps (handy shell, skyfire, fring, nokia email and putty mainly).
I also have an N800 that I love, even with all the restrictions it has. I admit the NITs are not very consumer friendly, but are open enough if you can take the time to set up scratchbox.
I have great hopes for the N900/rover, but as it's probably gonna be too expensive, I think I'll jump ship to android in the near future.
But, if maemo5 is solid enough for nokia to make it their smartphone OS, I could stay
Either way, I won't stop using my tablet, mer is looking good and could be great for the old tablets.