I use 1450 often. Mostly for Porters and IPA's.
For Porters, my average attenuation with 1450 is 70%, never getting better than 74%.
For IPA's, it's 79.5%, never getting anything less than 78%.
I assume that has to do with the fermentability of the wort, but I'm really not sure.
I really like the smooth mouthfeel, clean ferment and the general-purpose practicality of it. And it seems to go rather easy on this homebrewer when I let the temp slide into the low 70's. I haven't experienced any off-flavors from it yet.
My biggest hang-up with 1450 is that it is only available in liquid form and is simply not practical or cost-effective to have it shipped to me most of the year.