I really like Pianissimo's sound and kool, simple interface too. It's not a FANTASTIC sample-set, but it certainly doesn't suck, sound-wise. Most nearly any PC or laptop 2009 or newer, "should" be able to handle it without too much trouble.
However, I'm in total agreement with you - this nonsense of having to always "load it first" and even at that, it crashing and being a general pain-in-the-noodle has caused me to stop using it entirely. I bought it when I bought Mixcraft 5 from Acoustica. For the the most part, Mixcraft 5 has worked well for me. It lacks a few of the nifty "big guns" features, but it is a tremendous performer for only $79!
Another serious issue with Pianissimo, is that Acoustica are not supporting it much anymore and have not improved it since back in 2009. They still sell it for the regular ol' price though. It should be well-noted that Pianissimo DOES NOT play nicely with many other industry-leading VSTi plugins; namely Kontakt and SampleTank. If I try to use Pianissimo in a project where I'm using Native Instruments or IK Multimedia products, it will crash my DAW harshly and I've even lost data and had corrupted DAW files as a result.
ACOUSTICA HAVE NOT PUT THIS INFORMATION PLAINLY & CLEARLY ON THE PRODUCT'S HOMEPAGE. BUYER, BEWARE!
Nice little instrument. sounds great for only $68. Works well as a stand-alone app. Unfortunately, it sucks - and I mean sucks - for anyone doing more serious recording using other (industry-standard) products, due to the incompatibilities.
I own this, as well as TruePianos and Modartt Pianoteq Play (and now Stage), and I can honestly say that Pianissimo is a great complement to these products. It has a warmer sound (to my ear), than either of the others...but sheesh, I had no idea that it could actually cause a larger project to destabilize like this regardless of the DAW in use (stability is everything). I hope they fix it but, in the mean time, I won't be using it for any more of my projects.