Welcome to the forums.
I didn't have a GW GL1800 but I did have a GW GL1500. It was too bulky for me. It was fantastic on the road when I was traveling, but I most of my riding commuting to work and errands around town in congested traffic and parking lots. The GW was just too much of a monster to wrestle for that kind of riding to me. I find that I'm not alone with that opinion, even on the GW boards I've read. Not all but many share that opinion. Since selling the GW I've been on the search for the perfect bike that has the best of the Wing and not the bulk. Tried the Burgman 650... too light. Tried the ST1100... it was better but not quite the right sitting position for me. Nothing else was "out there" that was any better so stuck with the ST for a little while. Then along comes this offering from Honda and it didn't take but a few seconds looking at the specs and then afterwards reading reviews to convince me (and a few others here) this was what we've been waiting for. Have been riding almost every day for a week (missed last Sunday) and am more convinced than ever that this is just what I thought it would be. There are a few minor issues to cope with. Some are simply things to get used to, others are just different, still others can be adjusted in some way to resolve. But as I said, they are all minor compared with the overall package.
Just read through the posts in the Forums and you'll see. Windshield and mirrors are the two biggest things to be adjusted for. Most of us are going with the tall windshield or an aftermarket one. I am OK most days with stock but I think I would like the tall shield better for LD travel. I am also good with how I have the mirrors (and bars) adjusted, but some are opting for add-mirrors (there is a mount point on the reservoirs). Hope you find what you need to know if this is the bike for you and we'd love to have you stick around. Welcome, again.
Pros: seating position; comfy seat; wonderfully smooth V-4, with lots of lower-end torque; handling that belies its weight and bulk; excellent brakes (even on non-ABS standard model); undisturbed by wind;
Cons (these are the most common criticisms I've seen that are not gripes of my own): stock shortie windshield is inadequate for long distance touring; mirrors are difficult -- if not impossible -- to position for an unobstructed rear view; front suspension can be a little harsh over big bumps (but it does soften up some in time); very few factory accessories available yet, virtually no after-market; no factory cruise control.
I think those are the main ones on both sides. Personally, I absolutely love this bike, though I am admittedly biased. I've been dreaming of Honda putting that V-4 in a cruiser or cruiser-like platform, and for me, Honda has delivered better than I had ever hoped.
Feel free to post any specific questions or concerns you may have. There are enough of them starting to hit the streets that you'll get some objective responses.