I haven't tried the latest samplitude, but found the previous version to fall far short in comparison to Vegas. I had some major issues with editing and setting up the program to be able to record more than a stereo pair at one time. I never did figure out, the "multiple input" setup, after spending a couple hours with it. So I never got to truly test it out for true multi-track applications. I hated that it poped up a seperate record window, instead of just arming a track with an input meter like Vegas does.

The first time I used Vegas, it took me about 2 hours, to learn about 95% of it's features and how to use it, because it worked very similar to how I was used to working in a recording studio environment. Samplitude, I spent about 6 hours with, and couldn't do a session to save my career, if I had to. So I became, very frustrated with the program, closed out the window and never bothered to use it again. At that time, the price tag for Samplitude was $995.....not at all worth it.
I had similar issues with Logic Audio Platinum also. The only other program I found to be as intuitive as Vegas, was Cool Edit Pro, but at that time it didn't offer half the features as Vegas and didn't look very professional.

I heard these things about Samplitude as well, and decided to try it (they give you a full three month evaluation period - no restrictions on the software). Samplitude has a lot of features, which makes it much harder to use (or learn) than Vegas. I find the user interface of Vegas better - they don't give you any unnecessary controls, everything works pretty much as expected, and it gets the job done very efficiently. I also find Vegas' file handling better and easier to understand - it makes it much easier to keep track of your files (Samplitude pretty much forces you to use non-descriptive filenames, based on a numbering system). I agree that the setting up of recording inputs in Samplitude is a pain (I did manage to get it working, though).
Samplitude does have a virtual mixing desk which is laid out like a hardware console, similar to what many other audio programs have. This can be handy, especially since in Samplitude it allows you to save mixer snapshots. However, I find editing and envelope automation much easier in Vegas, and to me this is much more important than snapshots (which become problematic when using automation anyway). In Samplitude, you can't drag automation envelopes around as easily as you can in Vegas, so manipulating envelopes takes a lot longer.
One thing that really annoyed me in Samplitude is that only some controls respond to the mouse wheel.
Samplitude does seem to have a better implementation of MIDI. In particular, you can use a MIDI device to generate metronome sounds, and the synchronisation is rock solid. In comparison, I've found the metronome in Vegas totally unreliable and thus useless.
What concerned me was that SekD, the company that originally produced Samplitude, has given it up (and is in financial trouble now). I did get quick responses from the new distributor Magix, but they don't have a very informative web site (don't even mention forums such as this one). Supposedly the distributor has changed yet again...
I decided to stick with Vegas, and of course if you ever want to do video, there's no alternative.
Jens