I bought an 1150r as my first BMW, I got it coz I wanted a GS but couldn't afford one at the time, and had no real intention of going offroad then. I must say it's a great bike to ride, perhaps nicer on road than a GS

, though you'll probably be wanting a decent screen and seat if you're doing any touring. Course you'll probably end up wanting both for a GS too! I found 6th to be a bit high revving at 70-80, though they did do an optional longer 6th if you can find one.
Basically I'd say it's a great bike in it's own right, lovely to ride on the road, good engine, good in the corners, and looks beautiful (mine was in the limited edition dark ferro metallic

), nice riding position, can tour well with a few mods, though I always sighed longingly when I saw a GS on the road. I owned mine for a year, then realised I could finally afford a 1200GS and went for it. I've not really looked back, though I'd happily own an 1150R again if I had to.
As for the ABS question, it used to be a bit of a can of worms on the R1150R.net forums (worth a look by the way, if you're keen on the roadster, some great pictures too). Generally it's all down to personal preferance really. Some say you get less feel with ABS, it's more expensive to service, and more chance of things going wrong, especially if it's servo assisted, but my god, it doesn't half stop you quick if you need it to
Best thing you can do is go out to your local BMW dealer and test the different bikes out, dunno if you're new to BMW or not, but don't worry if you are, they're really great with giving out test rides.
P.S. Welcome to the forum!