I just upgraded my internal HDD by the way. Had the screwing problem that a lot of people have as they were on pretty tight, but needle-nose pliers fixed that issue. Otherwise, very smooth process. My 35GB of data is being restored as we speak.
I think one advantage is that once you've upgraded your HDD (mine is a 70 euro Fujitsu 2.5" 320GB with 8mb cache) in your PS3, you can use that for the PS3. Then, with PlayTV you can also use it for recording and watching shows. I'm very interested in seeing the interface in action even though I don't know if it'll ever be available where I live ... what I've seen showed something that is insanely more responsive than anything I've ever seen in these devices so far, and considering that Sony has a good record of keeping the software up-to-date, it could be a pretty good thing.
Once you add all these things up - video store, playtv, video playback from HDD for regular stuff, streaming video full-screen from the web-browser (that upgrade makes nice local websites with links a much more attractive option than they've been so far), DNA support, and so on, and all smooth and responsive, great BluRay playback, HDMI 1.3a output with full color support - it adds up. No idea how well it'll compete on the market in the end, but for those that can use all of those features, it's cool.
Of course, it would be nice if they don't take too long getting the video store out here as well, and maybe something like PlayTV in the U.S.
But we'll see.