The 150/150 is in a whole different performance catagory when it comes to takeoff and climb. That's it. That's the difference.
Yep! Just what Dan says. The 150/150 is a great airplane for two people, (and in our case, and a dog). You can really load a lot in that baggage compartment, (The newer ones with the full sized baggage area, that is). The 150/150 starts out 200+ pounds less then a 172 with the same engine . The 150 has only 9 square feet less of wing area then the 172. Compared to buying a 172, it is also much more inexpensive. In our search for a higher performance airplane, I first considered the older 172's with the O-300. They can be had in the $30,000+. I was informed by those that know that I would not be gaining much, if anything, in performance over the 150. Just a back seat. The Lycoming equipped 172's were out of my budget range.
So, for an economical two place airplane that will carry just about anything you want to throw into it and still get you in and out of just about any place you want to go, the 150 HP 150 is hard, if not impossible, to beat for the money! Even at Wayne's asking price for 150WW. You couldn't touch a similar Lycoming equipped 172 for under 60+ thousand dollars! And I could almost guarantee at that it would not be nearly as pretty as 150WW. And it would definitely lack the performance of 150WW.