This is for Orion Pro 2.7, the latest release. Coming from microLogic it's quite a leap - the MIDI editing facilities are somewhat primitive compared to Logic, and the mostly-enforced "you'll do everything with patterns" makes doing long-form work complex - BUT - the author (Rich) made a change between 2.6 and 2.7 that allows a single pattern to be up to 20min. long at 120bpm, which is Good Enough For Me. Other than that, audio track handling could be improved a bit - I'd like to see looping and some crossfading between overlapping tracks - but it does the job.
As to actual use, it's rock solid on my computer. The built-in synths are enough to get you going, and it's VST and VSTi support is second to none - all of my about a dozen VSTi drop right in and go. Mixer is excellent, I've have to fork over for Logic Gold to do better, and you can switch the EQ in and out (a nice feature). I've done a couple of quick tunes with OPro 2.7, nothing I'm ready to put on my MP3.COM band site but enough to be able to spend my Logic upgrade money on other things! There's a SIGNIFICANT learning curve if you're used to more 'classical' sequencers, but once you get over that it's a fast, effective tool for composition.
Biggest gripe: documentation. It's close to nonexistent. Thankfully there's a Yahoo group that's full of knowledgable users thats monitored by the programs author, so you can get answers to basic (and not so basic) questions pretty quickly.
Summary: I find it easier to use and more powerful than Fruity Loops. The program is always being upgraded, so I'm not worried about bugs (though I've found none yet). It's become the center of my virtual studio, between it, my computer, and my Fatar controller I'm mostly in business. You'll need a second audio app to record audio tracks (I use Cool Edit 2000 with the multitrack plugin), this is it's only "major" failing and the author has stated repeatedly he has no intention of adding audio recording to the software - that's fine with me, at least for now, as I can work with two programs without a lot of heartburn (and face it, Cool Edit has more power than the audio portions of many sequencers).
It's getting an 8 because of poor documentation and lacking MIDI editing facilities, but it'll never make better than 9 because of the lack of audio recording facilities.