If you still don't have a large monitor, it's time: buy one already. Then make Poly-Ana your next purchase. I honestly didn't think I'd buy another VA, and I certainly wasn't in the market for one, but I checked out Poly-Ana during the 1.1 public beta and never looked back. It inspired me to write a song based off a couple of presets, and I just had to buy it.
Sound: It's as simple as this: Poly-Ana is one of, if not the best VA's currently on the market. Try the (fully-functioning, timed) demo and experience it yourself. I did knock off a single point for the amount of alaising in the osc's even when using oversampling. At the highest oversampling level it's pretty much inaudible, but this can be a CPU killer. Freeze often.
GUI: Granted it's big, but everything's where it should be, and it's quite classy looking. The ability to create your own background .png has really added a nice level of customization. 2 points subtracted from the UI because of the size though.
Features: This is where Poly-Ana shines. What more could one want in a VA? Well, maybe an arpeggiator (feature request :) )...Even without the arp (my host should just have a good one), Poly-Ana still gets a 10 in this category. Between the 3 osc's, envelope options, LFO choices, multiple filters, multiple filter types, multiple legato types, etc., Poly-Ana has you covered on all fronts.
Docs are great, VFM is great, support is amazing, and I haven't had any stability issues with Poly-Ana. Anyway, you don't have to believe the hype, but give the demo a go. If I could only have one VA, it would be Poly-Ana.