Absolutely not worth the money. Both the original Sidekick and this new Sidekick are manufactured like absolute shit. I guarantee at one point in time you'll end up being pissed off at something not working. A button, a function, the screen, the signal, the reception, whatever. The devices drop like flies and although easily replacable, they just break too much. I'm on my 2nd Sidekick II and my sister is on her second or third, and I know a bunch of other people with sk2s and they've all been through at least one. T-Mobile will luckily replace the devices fairly easily, but that's probably because if they didn't nobody would buy this piece of shit because everyone would realize they break so easily. They're better than the original SKs, but still are quite unacceptable to me. I live in the Bay Area and have extreme reception problems, and for 70$ a month it's starting to get not worth it. If I wasn't in a contract now I'd probably get another phone. Though the thumbkeyboard is very nice and if all you want to do is use AIM and browse simple websites it may be good, overall it's not worth it due to all the problems and simple issues.
The ringtones all suck and the ones you have available to purchase are far too expensive for what they are (yay, shitty pop tunes that sound like crap).
The internet can have some issues due to the fact that there is no java. I mean, the internet is definately the only reason you'd want to get one of these along with AIM (DO NOT BUY THIS PHONE TO USE IT AS A CELL PHONE) but there's no java and on some sites it's annoying to navigate if you turn off images. And if you don't turn off images, it'll take much longer to load.
It does have a speakerphone which is nice, but the quality of it just always seems pretty shitty.
No bluetooth also kind of sucks, and there are a lot of features after using this phone you'd just wish it had due to simplicity. The PDA functions definately aren't advanced, they're dated. Whereas anyone with a phone made in the past few years will be able to customize ringtones, backgrounds, pictures, you'll be stuck with changing the ringtone from one shitty tune to another shitty tune or if you want to waste 2$ you can change it to a shitty popular music tune. This phone seemed to get popular because of that celebrity campaign, and I wish it didn't because it doesn't seem like Danger/T-Mobile's doing anything to fix all the problems it has. To me, it seems they're content with just shipping you new devices every goddamned time it breaks.
And believe me, it will break. IT WILL BREAK.