Honestly there is no comparison at all between a G2 and the crystal (as you would hope for the price)... well I suppose the audio is comparable!
Things are generally working very well for me at the moment, and I'm in a happy state with the headset after my questionable start. Image quality (in all aspects: colour, contrast, brightness, lens clarity, FoV etc) is a pretty big jump up from the G2 and I'm pretty sure most who try it coming from a G2, assuming their PC is up to the task, would start off with something along the lines of "wow". I did a little back to back with the Q3 yesterday and while the resolution is obviously a bit higher, its the sheer depth of the image with the colour and contrast that really changes the experience... seems much less like looking at a screen sometimes. Comfort with the Apache strap and the thicker 15mm facial interface is good, and the weight doesn't bother me much at all for most stuff, but anything involving rapid head movements will show up the inertia.
Software seems to behave well enough now (except for an annoying bug with play space that requires you to set the floor height each time), and tracking has greatly improved. Controllers still aren't on the same level as eg Quest 2/3 but are massively better than they were (and coming from a G2 in particular I doubt you'd be disappointed in the current state of controller tracking). Eye tracking is performing well, performance is particularly improved in Pavlov and DCS where you can use Quadviews and Mbucchia has the crystal well supported with PimaxXR and quad views foveated etc.
Missing features still - the wide FoV lenses haven't materialised yet, which should take the image to around 120ish degrees horizontal which would be a really nice thing indeed, the wireless (both wifi and wigig) are still MIA and standalone is currently pointless.
I think my biggest concern about the Crystal is that it won't age well. It doesn't really justify it's sheer size and bulk in the face of something like for example Quest 3, Bigscreen Beyond etc. I think the next year or two will see headsets that offer everything the crystal does but in much, much smaller form factors. At least with the supposedly upcoming 12k you are getting seriously high FoV and resolution in return for strapping over a kg to your head and looking like a hammerhead shark... so my gut feeling is a year or two from now the 12k might still make sense whereas the Crystal won't.
That said, looking only at what is available right now for PCVR for me it'd come down to BSB or Crystal (or perhaps the Somnium VR1 but that's unreleased and as yet totally unproven) and the answer would purely depend on personal preferences - both have their upsides and downsides and you wouldn't be wrong going for the crystal.