Great app :) 5 stars from me :) Really good video editor if you don't really need something as professional as Premiere or Final Cut Pro... but I think that even for professional use iMovie can be pretty good, if the project doesn't require some very advanced features or the level of tweaking something like the green screen videos that more professional video editors can have... you can still make a pretty good video with what iMovie offers :) and the UI is really nice and easy to use.
I should mention that you should update this page, since Apple made the iMovie free for all Mac users recently, so now it's freeware :)
BTW... I really don't understand why are some complaining in the comments that they find it "difficult" to use and/or giving the new version just one star and then writing how they like more some very old versions, even though those versions had less features and were in fact more complicated to use without actually doing a better job... I mean things like having to convert videos to that Intermediate format before editing them, which used to be very slow and used to consume lots and lots more space than an average .mp4 video does... and if you don't remember, iMovie 7 used to cause noticeable posterization of gradients if you were just importing pictures or .mp4 videos and relying on iMovie 7 to automatically convert them to that Intermediate format (if you didn't manually convert them first with something else to a format that iMovie 7 would accept without trying to convert it automatically)... Now, in newer versions of iMovie you don't have to convert stuff to that Intermediate format, you can just drag&drop mp4 videos directly to the timeline if you want and it's there... and you can start editing right away... and editing is not difficult too... the way someone edits in iMovie didn't change that much (some buttons were moved from being in the middle of the screen to the area above the video preview, instead of small icons for backgrounds and transitions under the video preview you now have buttons with text above the library area... some new features were added, the theme is different, but I don't see why would someone be confused by that), if you don't understand some of the new features very well, you don't have to use them all... Apple isn't forcing you to use each and every feature they add... you can still just split the video where you want (with CMD+B or by right clicking on it and choosing that option), delete the parts you don't need by clicking on them and pressing the backspace key, drag&drop some transitions that you like and export it... it's not difficult at all....
Objectively speaking, iMovie 10 is better than iMovie 7 or 8 and I gave you some of the reasons why... and there are also things in iMovie 10 that you just can't do with iMovie 7 or 8.
It's a good app and it deserves 5 stars in my opinion :)