I sat on the fence between Bonzai and Sketchup Pro for quite a while. After using Sketchup (free) for many years, I was on the hunt for something more. I took a look at basically every 3D modeling program available for Mac, and quickly eliminated most of them based on price and ease of use. I'm by no means a professional and was looking for software that didn't cost and arm and a leg, and that didn't take training to figure out.
In the end, and after extensively using demos and beta versions, I chose Bonzai, and with a few exceptions I'm happy with the decision. Here's why:
Bonzai is fast, capable, and dare I say it, fun. To get the inevitable comparison with Sketchup over with - there is none. Bonzai has more muscle. When Sketchup's bag of tricks is exhausted, Bonzai is just getting warmed up. The fact that Bonzai is a solids modeler puts it firmly in a different class.
At first the Bonzai interface seems awkward - most tools have additional modifier settings that affect the behavior of the tool. However, after making it along the learning curve, the way they've designed the interface makes sense, and allows faster modeling. For rectilinear modeling (e.g. millwork), you can model basically as fast as you can think about what you're modeling.
In a more general sense Bonzai takes an approach to modeling which I find "neat". Not very objective I know, but suffice to say that I find modeling in it more pleasant than other programs I tried. Also, everything you do has dynamic feedback on the screen. This makes Bonzai way easier to use than some other programs. For example, I own another modeling/CAD program which, in theory, can do everything Bonzai can do and more, but I find it so frustrating than I've basically given up.
Bonzai also seems to have enough depth to it that I can't see myself outgrowing it for a long time.
Now the down sides: If you want to produce more than neat looking pictures, you will need a CAD program to export to. Although Bonzai does ...
This is a very good 3D system! I'm trying to learn it or find my ways around it. II will consider getting a full license.
Quanderyously: I have been reviewing 3d apps for six months. I think I've tried them all. I bought Sketchup Pro, and I hate it! So far Bonzai, Cinema 3d, and e-On (e-crash-On and On) have the best "Mac" feel. Though there's no comparing the three, I have a pressing illustration project to illustrate and I think I'll go Bonzai because I can get up to speed quicker . . . It's super for that reason, the UI makes sense. What I don't like is that Bonzai doesn't package with a renderer, and If I get it's companion Render Zone, I'm talking the price of a much higher-end app. I don't like Form-Z or I would go that route. I almost bought each one based on its description but after using the trials for hours, and still not being able to make two boxes line up, I gave up in disbelief of how UIs could be so rediculous!