RealLPC is simply the best virtual guitar available in my opinion. It is pretty much identical to RealStrat (in case you own or have tried that one), except of course, the samples are recorded from a Les Paul Custom. There are a great many articulations (ie. Hammerons, Pulloffs, Pinch-Harmonics, Bridge-Mutes etc...), performance triggers (ie. Slides, Trills, Tremolo etc...), and the ability to create a custom keyswitch arrangement in order to trigger them.
I find it sounds much better than Realstrat (but that's a matter of personal taste). In particular, the bridge-mutes sound much more realistic, especially for rock-style playing.
The size of the application is surprisingly small considering all the options that are included, but that is because it combines samples with a lot of midi trickery. For example, there are no sampled chords; While chords can be triggered in "Chord Mode", the chords are combinations of individually-sampled notes. This obviously makes the library much smaller than it would be if all possible chords were sampled. One would think that sampled chords would sound much more realistic than chords comprised of individual notes combined, but RealLPC's chords sound very real. This is because the program doesn't just play individual notes at the same time to create a chord, it staggers the timing of the individual notes in order to simulate the effect of a pick strumming across the strings. In fact, the speed of the strum can be customized so that the chord can be strummed at any speed you like. There are adjustable pick noises as well. So while the sample-set is considerably smaller than some of the competing sample-libraries, there is considerable midi-magic used in order to compensate for this. I have a sample library for Kontakt that is absolutely gigantic by comparison, but I much prefer Musiclab's e-guitar offerings because they are very cleverly programmed, making them far, far easier to play.
I won't bother listing the vast amount of features, but suffice it to say that when I factor in the price, the amount of articulation/performance features and ease of play, I find RealLPC to be the biggest bang for the buck available at the moment. There is a learning curve, and you do need an amp sim (making it far more versatile than pre-amped/pre-distorted samples), but you can program some very convincing guitar parts with RealLPC as well as RealStrat and Realguitar (Realguitar being a collection of acoustic guitars).
My only gripe with it is that the pinch-harmonics aren't currently mapped to the right notes/frets. This was done on purpose, presumably because many users want pinch harmonics that match the regular notes, which isn't how a real guitar works -the pinch harmonics of notes played on certain frets are often different notes than their non-pinch-harmonic counterpart, and I guess some users prefer them to always match (real guitarists will know what I'm talking about). They're mapped realistically in RealStrat, but I guess they gave the average users what they wanted with RealLPC. Not a big deal though, and since I find that RealLPC sounds much better than RealStrat for my tastes, I can certainly live with it.
I gave the "Presets" rating a 1 simply because there was no "Not Applicable" option to choose. There are no presets. It comes with a default configuration, and you can create as many of you're own custom presets as you see fit, creating your own sets of keyswitches, altering the default pick-position, strum speed etc...
I wouldn't trade it for anything else out there at the moment.