I think lineform is really excellent. It looks like nothing when you first open it but it supports many of the features you would need for decent vector editing. Like many of Apple's own apps it shines by its simplicity. For anyone on an intel machine it's a must for vector editing. By the time you have launched Illustrator CS2 under Rosetta you would have finished your work in LineForm... I haven't used it during months so my review is about after two hours of use. I might have missed some bugs or on the other hand other great features. So far I am pretty enthusiastic.
For designing logos or vector icons it just looks perfect. Ultra-quick to launch, intuitive interface (the one-line help on top is quite precious, I'd like to see in other apps). If you want to import photos - directly from iPhoto, through a very apple-like media browser - and create more complex documents it can handle them pretty well. You can even apply CoreImage filters to your vectors (or imported bitmaps). In order to get decent speed you can chose at which resolution the filters are rendered. Fusion modes (à la photoshop) can be set for each layer. Good stuff.
You can easily create the equivalent of Illustrator masks by just using a picture from iPhoto as the fill type for your vector object. It's actually simpler. This also works with text. Just pick up a text object, set the fill mode to text and draw the object around it. The text will flow inside the vector object. You also get all the features you got used to from more expensive packages such as text following a path, aligning, layers, boolean operations and manually entering coordinates in an inspector.
You can export from Illustrator or other programs to SVG which this program can save and open correctly. It did at least for the documents I tried (logos) not sure how it fares with complex documents. And if you need to give the file to some printshop it can export to EPS and PDF. I could not try saving SVG documents but I assume that it if can load foreign SVG documents correctly it will save them correctly as well.
On the minus side, I think converting text to outline (quite a common task when creating logos) is not very intuitive. If you right-click on a text object and select Convert To Bézier it seems nothing happens? You have to use the menu and use Convert to Outlines. This also took me a while because the french translation uses 'relief' instead of 'tracé' to translate 'outline'. When using lots of effects things can get a bit slow but nothing unbearable.
After playing with it for a while my media browser didn't display anything anymore. But relaunching was so fast I quickly forgot about this bug.
On the 'very negative' side, I would say the complete blocking of the application after 30 days is not a very smart business decision. It takes time for people to find a pair of hours to evaluate a product they might not be using everyday. Like many people on this thread, I installed it when I saw it mentioned on some website, thinking I would evaluate it some day later. For some reason (no vector work to do) I didn't try extensively it until some weeks later and the tryout time was over! So basically I had to buy it to try it. In the end, I had to erase some 'secret' files in order to reset the trial period. It's absolutely stupid that I have to resort to 'cracking' abilities, just to play with the app and see if I liked it.
I think freeverse should just disable saving (completely) in the free version, and let people try it as long as they want. I only hurts the author, because after I got the time to play with it the only thing I want to do, is buy it (as soon as I can find out how to pay with paypal). I was very close to giving up. As an additional developer advice, I would price this app more like 49$ or less in order to get more customers first and then increase the price once you get more followers. 79$ seems a bit high given the current user base. It's high not for the feature set, but to get used to the idea of using some unknown program users need an incentive.
Wow, that was a lot of text. Short said: great app.