It's wonderful having a new version of MAMP Pro. I'd stopped using the old version because the developer seemed to have abandoned it, and between the built-in Apache server with Mac OS X and the new, easy-to-install MySQL, it was easier to roll my own local development server.
But now I'm back with MAMP Pro, not only for the ease of use, but for the little extras that are difficult to do when rolling your own. As opposed to using the built-in server, MAMP Pro also allows you to keep most of your development server files outside of the /etc/ folder, which makes them easier to work with, back up, keep track of, etc. -- especially through the OS upgrade process.
So far, I've come across only a couple of gotchas.
First, even though there seems to be an httpd.conf file in the conf folder inside the MAMP directory, it's not the one that controls the behavior of MAMP Pro. For that, you have to go into your /Library/Application Support/appsolute/MAMP PRO/conf folder. Because MAMP Pro puts all the NameVirtualHost and VirtualHost info inside the httpd.conf file, you'll have to take a step back from doing it the new Apache way, but it's not that big a deal. I have just over a dozen virtual hosts on my machine, and I set them up in what seemed to be a few minutes.
Second, MAMP Pro isn't really ready out of the box to run a local instance of Movable Type. WordPress is just about a no-brainer, but with MT, you can wander into blind alleys that seem to have no exit. I finally got mine to run by setting up my SQLite databases under the cgi-bin directory, rather than in the /db/sqlite section of MAMP Pro. Of course, even once you get it running, there are perl modules missing so MT throws error messages all over, but you can work through them ... at least to get your development instance working.
About the only thing on my wish list is that it would be nice to be able to store the MAMP and MAMP Pro files someplace other than the /Applications directory, because that's not the way I have may files arranged.
Bottom line: If you need a development server environment and don't feel like fighting with BitNami or xampp, or rolling your own, or making do with the lesser utility of a VirtualHostX-based system, MAMP Pro is just about the shortest way of getting there.