Popular iPhone photo sharing app Instagram captured the hearts of nearly five million users this year despite, or perhaps because of, a surprising lack of features. The super-simple photo app let you apply filters and post out to other networks. It didn't let you do much more than that.

The company has slowly added features over recent months and today unveiled a new version of its app with three big new features that could make a big difference in the ways we use Instagram. Those changes are upgraded user biographies, hashtag autocomplete and a new page to view all the photos you've clicked "Like" on in the past. Can Instagram keep its clean simplicity while adding more and more features? Time will tell, but these changes look to me like good ones so far.

First, user bios now include a URL field and a text field that you can populate with info and a link to another page on the web where Instagram users can learn more about you. That makes sense, as it's useful to be able to find out who a person is that started following you or Liked one of your photos - but it also removes some of the mystery of the experience. There was something a little intriguing about seeing someone Like your photo, clicking through to their page and still knowing nothing more about them than you could learn from their timeline of dreamy, filtered photos from somewhere in the world.

Right: The new Instagram profile pages are beginning to look more and more like some of the company's competitors' profile designs.

Hashtag autocomplete is something that the Twitter iPhone app has offered for some time and the feature is an attempt to get users to contribute photos and comments to a stream of topical conversation. It is, no doubt, added at least in part so that the commercial partners Instagram hopes to monetize will have some more solid ground in order to monitor their interests. If it catches on, though, it will also likely lead to some very interesting photo-discussions about topics of interest around the world. Especially once Instagram finally launches an app on more affordable Android devices (right now it's iPhone only) then it could become a service used to capture (and perhaps unfortunately over-filter) a photographic record of history unfolding.

The app now stands at an odd place between simplicity and a growing list of features.
Finally, the addition of a bookmarked-photos page in the form of a "photos I've Liked" view is a good move towards making Instagram feel more permanent and less fleeting. It's a cool feature for sure. How many of us use this app for quick capture but then make sure to send our best photos to Flickr as well, as that feels more permanent? This new feature adds an increased feeling of permanence to the photo-viewing experience.

The whole ethos of Instagram has been about speed, simplicity, lightness, a dreamy haze and a light layer of brief social interactions. There's still almost no web presence to refer to your photos there, you can't search for your photos or other peoples' photos.

The app now stands at an odd place between simplicity and a growing list of features. Will that mix serve it and its users well? Will the startup that did so well building a simple social mobile user experience do as well at growing its app up? Time will tell.