My beloved and well-worn Nokia E71 now has a pair of bigger and smaller siblings. The Finnish phone maker yesterday did a glitzy catwalk launch of the E75 (left in the picture above) and E55 (right), which also saw the unveiling of other new phones, at the swanky club Zirca (the former Ministry of Sound). Nokia held the Singapore launch in conjunction with its new product unveiling at the Mobile World Congress 2009 in Barcelona this week.

Here are my 2 cents on both models after a hurried hands-on session at the event:

Heavier and chunkier, though smaller in girth, than the E71, the E75 is comfortably one of the sveltest slider smartphones phones in the market. What I like: the 3.5-mm headphones jack, the motion-sensitive screen that pivots when you turn the phone’s orientation between landscape and portrait, and the fact that it is essentially an E71 on steroids.

What didn’t float my boat was keeping the screen size the same – 2.4-inch, 240×320 pixels – as the E71 despite the bulking up. Really, Nokia, why? Okay, you get a more spacious keyboard, but the E71 is already dandy in that department. So the payback for the extra bulk is for the numeric keypad and traditional phone styling.

The skinny E55, on the other hand, comes with the same screen size as the E71, as well as a 3.5-mm headphones jack, despite losing weight and being smaller.

The other big difference between the E55 and E71 is the half-qwerty keyboard. The E71′s 10-keys across and 4-keys down qwerty keypad is now halved width-wise, into a 5-keys across and 4-keys down keypad in the E55. There are two letters for each key. Press once for the letters on the left side of the button, and twice for the right. Unfortunately, my short time fiddling with this not-qwerty qwerty keypad is filled with typos from I guess my unfamiliarity with the scheme, as well as with the flat and tiny keys. Practice could make perfect – or not, for those with not-so-slender fingers.

For the more ham-fisted, the predictive text option (for both the E55 and E75), should make text input easier.

Both the E55 and E75 comes with a new, swankier interface – headlined by Nokia’s new email application. And both phones now feature flatter input surfaces, as opposed to the bumpy keys of the E71. While the new contact points look more chic, I still prefer the old bumps, which make typing more tactile.

So which Nokia will Goldilocks choose?

The differences in sizes and weights are not dramatic between the three bears, er, phones. The E75 is around 5mm thicker than the 10mm-thick E71, and a smidgen (12g) heavier. And it is actually 2mm shorter and 7mm narrower than the E71. This makes it one of the smallest (if not among the lightest) slider smartphones in the market today.

The E55 is wee longer (2mm) and slightly narrower (49mm vs 57mm) than the E71, while keeping to the same screen size. Most notable, however, is the weight-savings: 98g vs 127g. Shaving 30g off does not sound like much, but it is: the E55 feels noticeably lighter than my E71, which is already an insanely pocketable smartphone. I like!

Appetites whet? The wait for both phones won’t be long. The Nokia E75 is expected to ship in March while the Nokia E55 is expected to ship during the second quarter of this year.