Back in the day, the Sidekicks were among the most innovative phones around, what with their swiveling displays and killer messaging features. The Sidekick II blew me away back in mid-2004, so much so that I snapped one up for myself. But that was then, and this is now, and the Sidekick LX—updated though it may be—is looking pretty dated.

We can blame the iPhone for much of the Sidekick's long-in-the-tooth status. Love it or hate it, the iPhone and its touch UI has pretty much changed the industry, so much so that everyone's copying it (e.g., the Sprint Touch, the LG Voyager, etc.). While I've always been impressed by the Sidekick's intuitive interface, which (way back when, at least) practically seemed to be reading your mind, in today's wireless world, it feels a little quaint.

Anyway, let's hit some highlights—and lowlights:

Things I like:

• Form factor: When you look at their measurements, the Sidekick LX and last year's Sidekick 3 are practically the same size: about 5.1 by 2.3 by 0.9 inches. However, the LX manages to feel slimmer and more streamlined than the 3, and at 5.7 ounces the LX is more than an ounce lighter. Also, the funky flashing lights along the LX's "bumpers" never hurt.
• QWERTY keypad: The Sidekick's big, roomy QWERTY keypad has always been a highlight, and the LX continues the tradition with nicely backlit, rubberized keys that are easy on the fingertips. Well done.
• Vastly improved display: T-Mobile has been making a big deal of the LX's new dispay, with good reason. At 400 x 240 pixels and with technology borrowed from Sharp's Aquos line of LCDs, the LX's display represents a quantum leap over the Sidekicks of old, with revamped graphics to match.
• Intuitive UI: It may lack the iPhone's touch interface, but the LX boasts the Sidekick's impressive easy-to-use interface, including the "Jump" screen and an always-present menu option that rarely fails to deliver the options you want.
• Great e-mail and IM: The LX may not work with corporate e-mail accounts, but its e-mail client is still one of the best around for a consumer phone—and if you set up a Tmail account, messages are pushed to your device instantly (I used to forward my Gmail messages to Tmail, which got pushed almost immediately to my Sidekick II, and it worked like a dream). The LX's IM client (compatible with AIM, MSN, and Yahoo IM) is super-slick as well, and it runs in the background.
• Standard headset jack: Have a pair of pricey Shure earphones you want to use with the LX? No problem: a standard 3.5mm jack is included (and you won't need an adapter, a la the iPhone).
• MySpace Mobile: Got a MySpace account? Sidekick's new MySpace app is a slick, easy way to ping pals on your buddy list or post messages and pictures.

Things I don't like:

• Half-baked MP3 player: The Sidekick 3 came with the handset's first stab at a music player, and the LX's version is basically the same version. You can play MP3s and AAC music files, but subscription music services aren't supported. Also, you still can't view album art, and there's still no equalizer, no video playback, no over-the-air music, no stereo Bluetooth support, and no external music buttons (besides a volume control). While I appreciate how the Sidekick lets you play tunes in the background, the LX's music player feels like something from 2005.
• No touch UI: Yes, I praised the Sidekick LX's interface just a moment ago, but as an iPhone user, I can't help but be disappointed by the lack of touch-sensitivity on the LX's screen—it's the wave of the future, and the LX's UI can't help but feel like yesterday's news. Too many times while surfing the LX's various screens, I found myself wondering, "Why can't I just touch that?"
• Outdated Web browser: The Sidekick's on-board Web browser was amazing back in 2004; today, it's looking seriously dated. Yes, it still renders big HTML Web sites that standard phones can't, but pages look badly jumbled, and pull-down menus and other on-screen inputs are tough to manipulate. With heavy competition in the form of Nokia's top-notch Web browser and Safari on the iPhone, the Sidekick will have to do better to stand out from the crowd.
• No 3G: T-Mobile has yet to launch its own 3G network, so EDGE-only data access on the LX is a given. Still, that leaves it several feet behind the starting line compared to such phones as the Palm Centro and the upcoming Voyager, especially when it comes to streaming video and music downloads. But wait—the iPhone doesn't support 3G either! True, but that leads us to...
• No Wi-Fi: T-Mobile is no stranger to Wi-Fi-enabled phones—witness the Wing and the new BlackBerry Curve, both with Wi-Fi—yet here is the LX, with no Wi-Fi in sight. The non-3G iPhone can do over-the-air music downloads thanks to Wi-Fi—not so here. Even worse, T-Mobile missed a golden opportunity to make the LX a HotSpot @Home phone (which allows for Wi-Fi phone calls).
• No GPS: Not only is the LX lacking integrated GPS, it's also seriously in need of a garden-variety mapping application, which is getting to be standard issue with even the most basic phones.

Bottom line:

The Sidekick line deserves a deep bow for its nifty design and past innovations, yet it's fallen seriously behind the times. Such features as streaming video, music downloads, Wi-Fi, and GPS are practically givens in the latest high-end consumer phones, and with its high-end price tag of $300, it's fair to expect such tricks from the LX. Sadly, I can't recommend the LX unless you're a die-hard Sidekick fan. Instead, save your money for a handset with today's features, such as the iPhone, the soon-to-be-released Voyager or the Palm Centro (which offers 3G, streaming video, and push e-mail for just $100).