I use a tascam 424 MKIII as the foundation for my home studio. The Blue Tube was a good addition for a number of reasons.
First off.. when you use it RIGHT you do get tube warmth added to your sound. Yes, you can get noise.. ever see a tube that couldn't be pushed into noise? But I've compared this to the same tube in my digitech rp7, and my fender hot rod deluxe.. using guitar.. and the blue tube is as quiet, and they all sound very similar when you have the settings duplicated as close as possible.
I love this for my vocals, and my bass, especially...I use the blue tube now and then with my Nady CL5000 compressor for clean guitar sounds.
I want to add another blue tube so I can have it for the four main channels of my studio.
I'm glad I bought it, I'm happy with it's behavior and construction.
If you're recording at home, and are on a budget, there ARE good units out there that will fill the bill.. and this is one of them.

Feature:
BT has everything you'd need, and the bal/unbal input jacks are very cool.

Quality:
Seems very solid- apparently you can run extremely hot signals through the input without frying it.

Value:
Can't get a better two channel preamp for the price.

Desirability:
Very sexy. The ladies love it- all I need to get lucky is my trusty Blue Tube. BT is a classy looking unit, and it doesn't take up a bunch of space like some of those non rack mounted units with the tube stickin out the top. The sound really suits my taste- which is usually never satisfied. I run all my digital gear through BT to warm things up, and for that sweet mildly dark tone.

Sound:
Heavy, pretty dark. Very clear- you can dial in tons of drive before getting distortion.

Support:
Haven't dealt with Presonus, but I'm sure they're nice people.

Overall:
I'll use my Blue Tube forever. That may be the kind of stand up guy I am, but the preamp is worth it. I probably won't get another one until it breaks beyond repai, which hopefully is never- I also hope the tube is replaceable. I recommend this unit all the time, too. Unless you really dig an ultra bright tone on everything, this is your next preamp.

Feature:
does everything i need it to.

Value:
for the money, you can't get much of a better preamp.

Desirability:
hey, i bought another one, so it must have done something right. it's a nice looking, 1/2 rack space unit.

Sound:
Sounds really nice, a little noisy, but it's tube, so - I have two of them and use them as preamp/warmers for my DAW. does a nice job of thickening up mics for vocals/guitar, and is great for direct on bass.

Support:
never needed any

I use Neumann condensers and my bass thru this. This wakes the microphones to sound 'active', and the Tube Drive can add even some effectious overdrive in the signal if wanted. I was blown away from what it did as a electric bass preamp! Made my passive bass sound so much alive. I am thinking of getting a BlueMaxx next to my Bluetube.

whether you're working with mics or even acoustic guitar pickups, this pre-amp works equally well - the only change I would make is to have separate switches for phantom power for the two channels - if you have phantom power on, it goes to both channels and you don't have the option of sending it to just one

I have had my Presonus Bluetube since X-mas, 2000. What can I say?

EXCELLENT! Purity, no BS construction and function. Absolute brilliance. It is soooooo worth the price!

Use it for vocals, synth sound enhancement or thicken up a track in your song mix by piping through it!

You will not be disappointed for the price.

I was excited about this little wonder when I read the rave reviews, but I couldn't help wondering how an half-rack mic pre at $75 a channel could be decent. When you take turn up the "drive" knobs it gets rather noisy, and I wouldn't exactly call it "tube warmth". It has its uses, and ultimately I do not regret having bought it, but I wouldn't buy a second one. I have used it in between mics and a power amp to drive a small practice PA, as well as with an 8 track analog tape recorder. I wouldn't recommend using it to record the most important tracks on a song if you're using a direct to tape approach and bypassing the mixer. It certainly would be fine for something like drum overheads or other drum parts, perhaps bass guitar. But I wouldn't count on it for vocals, acoustic guitar or another featured performance in a tune. I prefer units like the Joe Meek VC6Q that give you eq, compression and mic pre all in one. I tend to rely on compression when I'm tracking to keep my signal levels under control. I've put the Blue Tube in line with a compressor with better results, using Alesis 3630 or the Behringer Composer.

there are some problems:
1. no power switch
2. no LED indicators for phantom power, phase inverter, or 20 db pad
3. the gain and driver are "backwards" on the right hand side, supposedly to make them symetrical but it is really confusing to operate. i wish they were [left drive] [left gain] [right drive] [right gain]
4. there is a lot of hiss (but i have no other preamps to compare it to...)
5. the gain and drive dials create A LOT OF NOISE when you turn them -- a big crackling sound
6. the manual does not say what happens when you use phantom power on your mixer and use the XLR outputs on the bluetube -- will it blow up? i dont know...
7. the manual does not say what happens when you use the 1/4" inputs and turn on phantom power. can i use phantom power all the time? i dont know...

plus side:
1. it is super cheap
2. it has 2 channels

i guess you get what you pay for, but i cant pay for much so i could only get this...

i still need to check out how it sounds with vocals on a rode nt1, but it helped a lot with acoustic guitar and helped warm up the midi module a lot (roland 1010).