I make ringtones for a living; therefore I need a reliable General MIDI sound module.
For the last two years I have been using BS-16 full-time (for about 40 hours a week) and it hasn't given me a single problem, let alone crashed!
It is extremely CPU efficient, and the sound quality is good.
It's cross-platform compatibilty allows me to recommend it to our Mac-using programmers, which makes it easier to keep our output consistent. (They haven't reported any stability issues either!)
The gui is unlikely to win any beauty contests, but it gets the job done without getting in the way, and most of the time I don't even need to launch it as the plug does a pretty good job of interpreting sf2 parameters. (this is why I gave it a high score for "presets")
What more can I say? If you need a GM sound module, this one (loaded with a suitable soundfont) is the best I have been able to find, and of course it is not limited to General MIDI, as it is as flexible as your soundfont collection..
I want to second everything pljones said previously, and add a few remarks. I purchased version 2.0, found a couple of soundfonts that did not play correctly, posted them on my website and sent Bismark's author the links, and he downloaded them and corrected the problem, resulting in v2.0.1. I found a couple more that had problems, and v2.0.2 is the result. The author is trying hard to perfect this player, and is very receptive to constructive input.
I have an SBLive, and in my opinion, the only other soundfont player that renders some soundfonts a little more accurately than Bismark is sfz (or sfz+). But I tried sfz and it required more CPU than my system could handle at very low latencies. Bismark, on the other hand, sounds very nearly as good, and consumes less than half the CPU on my system. It also has continuously varible MIDI dynamic response, which I find more useful than the set of fixed dynamic curves provided by sfz.
It did not come with any presets, but it did allow me set up a fairly complex set of instruments from my own sounfont library and routings in Sonar, and they save and reload just fine as part of the song.
Because I have a huge soundfont library and only one SBLive, I am finding this VSTi to be one of the most useful virtual instruments in my studio.
I just wanted to add that I have recently received a free upgrade to v3.0.2 from Bismark and I am very pleased. If anything, this new version is even easier on CPU, certainly no higher than before. The new included chorus and reverb, while not spectacular, are quite usable, and pretty easy on CPU as well. Overall, it sounds better, and some sf2's that did not sound exactly right under v2.0.3 seem to work fine now. So, this plug keeps getting better and better.
Bismark BS-16 is a step (or so) up from BS-1. It is a 16 channel multi-timbral, GM Soundfont soft synth.
"GM" - it knows that Channel 10 is for drums.
The user interface is fairly intuitive. Apart from responding as expected to MIDI prog change messages, you can set the prog on each channel by hand, including setting a channel to be a drum channel. There's also plenty of other knobs to twiddle (but I tend not to).
Soundwise, it's as good as any Soundfont synth I've heard. One big advantage is that it doesn't eat as much CPU as, say, VSampler -- because it's only trying to do the one thing. For my Celeron 400, this is very useful - fewer drop outs at higher polyphony.
The feature-set is okay - there's no on-board automation of controls but it supports MIDI automation, so that's not a problem. It even supports multiple soundfonts!
The documentation is, in my opinion, adequate: the non-beta version ships with a copy of the web-page that fully describes the capabilities of the VSTi. It doesn't really need much in the way of tutorial/HOWTO, so the guide on the web page is more than enough.
"Presets" - mmm... Well, it lets Muzys reload its settings. I've not really investigated this area.
Customer Support - good! I dropped a bug report in (a nice, reproducable fault) and a new beta appeared a few weeks later including a fix and a thank you.
VFM - I'm more than pleased to have paid for this VSTi. Along with MIDI-OX, it's probably the most important part of my set up :-).
Stability - BS-16 is still in beta but seems quite stable.
I think it's time for a 64-bit version of BS 16. I am switching over to 64-bit Reaper. BS 16 is the best sf2 player/VST instrument I have used. It is especially good at tracking my MIDI (FTP) guitar, and by far the most accurate, even with pitch bends. I'd gladly pay an additional charge for a 64-bit version of equal quality.