Not sure what the previous poster is talking about with the reception of the BlackBird. I have this setup in my 4Runner with the external antenna attached and mounted under the dash (i.e. factory GPS antenna location.) and have no reception problems at all. I do agree however that the resolution of the BlackBird is not the best coming out of the HU (looks great on the BB's internal display), but it's still very readable. The HU itself is a great unit, works really well an iPod (or two if you get the optional ipod full speed cable). The interface if very responsive and crystal clear. My only real complain is the fitment inside the dash of the 4Runner, in the factory locations on the mounting bracket the HU sticks out too far (same as the urban runner TomTom unit). I drilled out the factory mounting bracket and set the HU back about another .5" . Looks a bit better, but still not to my liking, plus there's a gap (about .25" above the HU and the dash.). The problem is the factory mounting on the 4Runner (cause any std. dual din has the same mounting locations) and there aren't any really good dash kits for the 4Runner.
So in other words I'd say go for it. If you want a better navi, go with Alpine's DVD nav. Has a higher resolution as well.