I don't care very much for big numbers in hardware, as long as it is decent. (However the device shouldn't be larger than it is. Those huge phones of these days are getting impractical to carry.)

What I do care is software. These devices have desktop-like power, yet Windows Phone and iOS treat users like mentally challenged with their stupendously backwards implementation of the multitasking concept. Concurrently (ha!) they are compatible with just about nothing that exists yet, so that every piece of software has to be re-implemented - poorly, often.

These devices can bridge desktop and mobile use. The N900 and N9 are powerful enough to run a full desktop OS, and with some hacking already can. Hook up a HDMI display, bluetooth keyboard and mouse and voila you can run anything from LibreOffice, Netbeans, full browser, remote desktop and what have you. Mind you, this is impossible with iOS, probably impossible with Windows Phone and quite hard on Android.

Also, the platform really should be open. Locked bootloaders, TPM's which won't let me add keys, closed specifications should be avoided like the plague. Would you accept it if your PC can only run Windows 7? Heck, even Macs allow you to install other OSses.

Of course, existing and open systems and protocols should be supported. I'm still flabbergasted the N9 lacks (official) SyncML and XMPP support. UPnP was only just added. IMAP support is still sub par compared to e.g. Thunderbird. Instead I'm greated with proprietary and privacy-damaging things like Facebook, GMail and Dropbox.
Windows Phone, for that matter, is even far worse in this regard: you can't even send or receive a vcard over bluetooth. Bluetooth tethering? Nope. Unbelievable.

Alas, the big hardware numbers mean nothing if the software limit the power-use of the device. Software is key, and that goes far further than the number of apps in the store.