The PreSonus BlueTube is a really easy preamplifier to use. Each channel simply has knobs for drive and gain while it also has buttons for a pad and phase. There is also a single phantom power button that applies to both of the channels as well as metering for each channel that shows the overall level you are getting from your signal. I've never had any problems whatsoever manipulating this preamp and I don't think that too many people will have trouble with it either. The manual for this is put together pretty well but it really isn't a necessity as it is easy enough to use on its own.
Even though this is a tube based preamp and does have some warm to it, I like this preamp mostly because it has a good deal of clarity. These preamps are suitable for just about any application but I use this mostly for electric guitar as I find it to work best for this and I have other options for other applications. While I wouldn't really say that this preamp colors your sound, it definitely does have its own sound to it.
While I can't say that I would recommend the PreSonus BlueTube to professional engineers or studios as I don't believe the overall sound quality is up to par, I would recommend this to home studio owners looking to get a very reasonably priced set of tube preamps. They do have a pretty good sound but the price is really the best part about this as they give you a lot of bang for your dollar. If you are a home studio owner looking for a cheap set of tube preamps, I would recommend checking out the PreSonus BlueTube.