The Helios 40-2 85mm (actually 85.18 mm) portrait lens is very much a cult item. A new one from Russia runs for about $450 and vintage Soviet copies will often run over $300. Photographers have even started taking them off of the Soviet night-vision devices that utilized stripped-down versions of them, even though those are locked into wide-open f/1.5 aperture.
Everyone who isn't trying to sell you one is in agreement that there's nothing great about its image quality. It's also not very convenient to shoot with. It's quite large for an 85mm, and it's absurdly heavy at over two pounds -- almost twice the weight of the Sony camera body I hooked it up to.
So why is there a market for it? Because of its very unique, weird, swirly bokeh. Click here (all links open in a new window) for a great example from the lens's flickr pool. If you've got just the right background - usually branches and leaves with abundant light - then the out-of-focus light will melt and funnel around the center. Another typical example. Even when you don't have the perfect background for that effect, you'll still get unique results. Not usually pleasing in my opinion, but unique.
I gave the lens a try for concert photography. I've never seen anyone else use it for that, but I figured it's not an all-bad fit. The fast f/1.5 is good for a concert's low light, and I like using portrait lenses for concerts. You usually won't be able to fit the whole band in your shot, but a lot of concert photography is ultimately one or two-subject portrait photography anyway.
I took it to a small-venue show and decided to shoot exclusively at f/1.5. Obviously focusing at that setting was a challenge, especially since the focus ring has a fairly long throw. And even when you do get it in focus, it's soft at f/1.5...