Portal Pro is a set of test chambers focusing on solving puzzles locally rather than using complex fling techniques. The goal here is that the solutions are hard to come up with but easy to actually do.
This review may contain spoilers
At first try, this mod proved to be WAY to hard for me, but after the determination and boredom (had nothing to do) I decided to give it a second try and, knowing some of the solutions it was pretty cool, however, the end kinda killed it, it was WAY too difficult (well, it was pretty simple, but the manuevring kinda got bored) and the post-boss-explosion also kinda killed it for me, there is simply no way knowing where to go next in some areas.. but overall, I would still recommend the mod.
PROS : Nice gameplay, puzzles, new AI voice.
CONS : Some puzzles not properly explained, some areas boring, and ending kinda sucked