I didn't give a great review of Frohmage, but now I can let rip with a review of the other Ohmforce plugins - As with all of theirs, they are flexible and very very distinctive. Haematohm is possibly one of their weirdest ones released - and I love it.
Sound - It's a frequency shifter - in practice it sounds like a pitch shifter but not quite. Basically if you put, say, a drum loop through it, it'll sound like the drums are being pitched up or down, but it's far more extreme than that, as it's shifting the actual frequencies in it to huge ranges away from normal up to KHz or down to double figure Hz. The difference you hear from a pitch shifter is that it retains the original quality of the sound much more than a pitch shifter would (sounds odd I know) - whereas if you pitch shifted a vocal it would sound like Smurfs, Haematohm retains the quality of the speech somehow - difficult to explain in words. An added bonus is the delay which is fed back into the shifting. This means the delay can constantly rise or fall or both with the LFO - similar to what you get in some of the better h/w FX units. This can create weird alien landscapes or be useful in moderation with drums or hats to subtly alter their "pitch" and give a more human feel and sound. Or be used as a kind of chorus to vocals - In fact you could use it to double track a vocal line, but pitched down a little without all the hassle of either rerecording the vocal or time stretching/pitch shifting via a sampler. Not realistic if overdone though.
One trick Pony? On first hearing and some extreme FX, you might think so, but as mentioned above it has extremely useful real world applications that can save you an immense amount of time and effort over doing it the traditional way. One of its presets is called Human Touch (if I remember correctly) - try that out on drum lines or vocals and be surprised at how subtle but effective it is. Or you could feed a synth note into it and make what basically are arpeggios - musical if done right, or weirdly alien if not (which is good). You can control how much shift is introduced, how much delay, and how much the delay is shifted - marvellous. It can also be a great master or group effect for the odd bit of weirdness - pitch up a whole group, or the song at the breakdown or end of an intro as a crescendo - or just use it on cheesey techno snare rolls - instant in-yer-face effect!
VFM - I got it when they did $10 specials so it was an absolute bargain - now it's more realistically priced, so maybe you should test it out first - it's one you won't use regularly, but when you do it has no equal, especially if you want weird. So weigh those 2 things up.
Features - didn't give it 10/10 because it doesn't do everything you might want, but that's small fry compared to how individual it sounds when you do. It's not a studio essential, but if you like odd FX they don't come too much odder than this, but it's eminently useable.