[General Topics] Gadgety:
I have to say I'm tempted by the N900. Up until now I was totally convinced my next device would be WinMo. Here are the pro's and con's for my usage pattern:

In my opinion what speaks for HD2:

Huge screen; fast processor; very slick looking interface; runs all the software I want, most notably the MLO outliner and backs it up on the PC,connects to my SonyEricsson BT watch (thanks moneytoo!) which displays caller id, rss feeds, sms's, mails, enables answering mails with a pre-set message with push of a button without having to take the phone out etc (some 40 or so functions run from the watch); can run Garmin XT which to me is the best GPS software out there due partly to the user community in South America updating Garmin maps almost weekly (which can be extremely valuable); the largest user community base in XDA-developers (with 1.9M members, close to 260K active members, over 4M posts in 323K threads), edits all MS Office programs

Against:

Capacitive screen, not fully flash enabled browser (?), not as good camera, no webcam, no VGA-out, only 16k colors, expensive; not as pliable and adaptable - will get older quicker than the N900, I suspect.

What speaks for the N900

The N900 obviously has way better browser/webaccess, has a frontal cam that works for chatting at least between Nxx0 units, and possibly with PC's as well (it works on the N8xx, which are older devices, but it may be blocked by the service provider on the N900, this is an unknown yet, if it does work, though it's a huge plus, to me) a better, and protected rear cam, better video filming and, possibly, playback, 32 gb of internal memory, vga out, runs Open Office; I would hope it has better phone and sound quality, but don't know;resistive screen viewable in sunlight afaik (I prefer resistive as it allows for handwriting and precision), 16M colors, ability to run Debian based software - although I have no idea whether that software will do anything useful for me, more colors on screen

Negative on the N900:

the biggest drawback is it doesn't run some key software I'm dependent on, such as a really capable outliner like MLO, enabling multiple contexts with backup on a pc, afaik [anyone with suggestions for a solution are welcome, I've looked into NoteKeeper but it's not quite there, yet]; another biggie poor GPS apps that in addition requires full on connection to work afaik - although I hear that today Nov 13, Sygic released a version for Maemo - but I would prefer Garmin for the SouthAmerican maps; I know this may seem minor to most users, but it doesn't hook up to my SonyEricsson BT watch which is a nice gadget and support to the mobile; doesn't [yet] allow editing of MS suite documents; doesn't play FLAC files; smaller screen; and although the Maemo.org user community is very helpful, it's smaller than XDA, and most of its 38000 active users seem to be hardcore Linux programmers, and I'm not sure I can speak there "language," whereas I've been hanging around XDA to understand at least hardSPL, ROMs etc.

I'm no programmer, not even really a superuser of any of these. N900 shows a lot of promise on the software side, but will it be fulfilled? It will probably improve more over time than the HD2.

An alternative would be the Acer neoTouch, as it is WinMo and has a resistive screen, but then it doesn't enjoy XDA-support (although there is a small user group on here anyway).