Watching Season 4 will be in some ways very much unlike the previous seasons - sure, the basic premise of course remains and many of the characters are familiar (and the ones who are not are no less gifted). The positive development in my opinion is that the whole show calms down a bit and istead of jumping between alternate futures episode to episode, there seems to be a consistency of theme throughout the season.
The new addition is the Carneval - a way for a group of people with abilities to hide - and as for people, Samuel is the main new character. Without spoiling any of it, the majority of the show links to / revolves around the Carneval and Samuel, while at the same time also revealing more about Claire (the cheerleader, who now is luckily out of the cry 5 times a minute phase for good) and Noah Bennett. There are also two subplots focused on Gabriel and Hiro respectively, which work rather neatly.
The added focus, and as a result a slightly slower pace of events in my opinion really adds to the franchise - it removes some of the frantic elements from the previous seasons and allows the story to build more slowly, also giving Kring more of an opportunity to build a more solid and bettr rgued story in the process.
If you liked the previous series, this one should definitely come as no disappointment, in fact, had you not watched the series from the start, Season 4 might be a good place to immerse yourself, before going through the rollercoaster of the previous three seasons.