The professors of Hogwart's Castle shown here are all in set 4842, the 2010 version of Hogwart's Castle. Dumbledore, McGonagall, and Snape have all been available in some variant previously. Professor Flitwick, however, is making his LEGO debut.
Minifigure Parts and Accessories
Professor McGonagall is composed of four parts: wizards hat, head, torso and dress slope. The overall design is very similar to hp022; however, the dress and torso is a darker green, while the head and hands are now in flesh tones.
hp072, but is actually a new variant. As seen in this review from Eurobricks member Ras 74, we can see that this new design has a dual-sided head and torso print on the front and back.
Professor Snape is made up of four parts: hair piece, head, torso, and legs. Prince Dastan's hair (part 88283) makes an appearance here in black. The head appears to feature a new print. The torso is very similar to the one used on figure hp082, except the print outline is gray instead of purple as seen here. The legs are a basic black set.
Professor Flitwick is composed of four parts: hair, head, torso, and short legs. Flitwick's hair a bowl cut style (part x219) that has appeared on other figures like Dr. Octopus and Ron Weasley. The head features a new, and humorous facial print. The torso adds a new bow tie design to the LEGO universe. The short legs are part 41879.
The only accessories here are 4L bars (part 30374) in a variety of colors standing in for wands. Although not particular to any one professor, there's also a 'sorting hat' that comes with the Hogwart's Castle set - a witch's hat in brown with print to resemble the hat's face.
Army Building Potential
None of the professors have a strong ABP. I would classify all four as "low".
With the exception of Dumbledore, Harry Potter fans have to get three new minifigures for their collection. The biggest draw among all four figs are the torso and dress slope of McGonagall. Since female figures are scarce the overall dress combo could have appeal in other custom applications.
(Picture via Eurobricks)