
Actually, BT can't entirely circumvent Twitter's 140 character limit, it just extends singular Tweets to two Tweets. This works, though, because large BT Tweets will show up at the same time, and will indicate which comes first by calling itself 1/2 or 2/2. This works for the most part, but it does provide problems as it can separate hash tags. If posting a big Tweet, and the hashtag is at the end of the post, it will show up on the second post, but not the first. I haven't found a way to get around the problem. If anyone knows a way around this, do tell. Still, the big post feature for BT is good for when the user has something to say that just cannot fit into 140 limit.
It's easy to change the size of posts from 140 characters to 240 characters.

To make Tweets large, the user must simply click on the "Posting" tab, and check the "240 character mode" option. Then, Tweets larger than 240 chracters will post as number 1 of 2 and 2 of 2.
Another interesting, though less well-known feature of BT is its ability to let users post using 64 special characters distributed across two different pages at the click of a button. Performing this taks is simple; one must simply click the "Special Characters" button on the left side of the window which is directly under the "Text Control" button. Page 1 of the special characters looks like this:

The second page of BT's special character page looks like this and is equally easy to use:

Also, BT can post to Friendfeed as well, another social networking site.
Dragging the BT button to the top of the most recent version of Firefox was no problem at all. Chrome, Safari, and Internet Explorer are supported as well, though there seems to have been a small problem with IE (surprise).
Though BT is simple to use, its site added a tutorial page anyway. The tutorial explains the service while using it. The explanation of how to perform various things with the application are spelled out in the application. It's pretty clever.

Aesthetically, BT is Spartan, and not as in Frank Miller's 300 spartan, but as in bland-bordering-on-ugly spartan. But that's okay; the application's main draw is its usability, not its aesthetic design. In a future iteration, I'd be happy to see designer make the application at least a little more nice to look at. I'll take function over form any day, but I'd rather have both. And with many Twitter Apps looking increasingly sophisticated and sharp, it would behoove the makers of the app to make it nice to look at.
BT also has a FAQ page, though it's kind of short because it's such a simple application.

Twitter's prime academic purpose is to transfer interesting information. I know that, sometimes, I see sites, and intend to share them, but never do. BT works so seamlessly that it makes this transference of information easy. There isn't much to say here in terms of discussion, actually. When you find something you like, you can easily link to it. BT, and other Twitter apps like it, can help users add to the Twitter discussion. While the discussion is not a two-way street as it were, users' ability to put links in Twitter make the site an increasingly more important repository of information all the time. The more people use Twitter and the more easily people can put links on the site (thanks to the bit.ly tool), the better the site will be.
Looking at a list of Twitter applications on Squidoo, it's clear that many apps are limited. But practically speaking, BT can only be used sometimes, and in certain instances. While one could use BT all the time if he or she was interested simply in posting to Twitter, I don't believe that enables the full Twitter experience. Twitter, I believe, is much more interesting when I can see what everyone else is saying.
By fixing the one glaring flaw of BT- its lack of full Twitter functionality, this application could have become indispensable. It already has two notable advantages going for it in the form of its post from anywhere and its built-in url shrinker. Enabling users to engage in conversations with friends and see other people's updates would have been icing on the cake.
BigTweet is certainly a good application which does what it claims to do, and does it well. I just wish that it did a little more- that it would integrate full Twitter functionality into the application. Come on, people, make it happen! Still, I can recommend BT for anyone who just needs a little more space, and doesn't want to keep a special tab open to make urls shorter.