>>34502964PRO actually has all the first four regions, and the first 6 gens of Pokemon.
>>34503125Nothing game-breaking. They undermine the world design by artificially blocking you off in areas for no reason, for example in Ecruteak you can't explore the east or west routes until you beat the gym even though you can't advance the story without the badge since it lets you surf, and this prevents you from catching Murkrow to help counter the gym. They basically block you off artificially in every place that the original Pokemon blocked you off naturally. They also force in some weird story stuff and occasionally give the MC a lot of poorly written, unnecessary dialogue. They also add really bad stealth mechanics to some of the Team Rocket areas for some reason, and there are a bunch of other little things that tend to be kind of grating.
However, they have a lot excellent design decisions that really streamline the Pokemon experience like speeding up leveling, showing IVs, allowing you to dig from one end of a cave to the other once you've passed through it once, giving you money when you beat wild pokémon, letting you overwrite HMs and overall reducing the number of HMs to Cut and Surf, and numerous other things that make it a lot more enjoyable. I don't mean to shill but it's a lot of fun and the community is awesome too which is a bonus.