Kinda depends on how hard you bring it. And Beta does require dumbbells or resistance bands.
In the Alpha phase, there are a couple workouts you'll probably find pretty easy coming off Insanity: Alpha: Cardio and Alpha: Speed 1.0. On the other hand, Alpha: Total Body Circuit and Lower Focus will probably be a little tougher than you might expect, but still very doable.
Beta really gets into it, though. You shouldn't have any real problems with Core Cardio or Ab Intervals, but the addition of weights in Rip't Circuit and Upper Focus brings a whole new dimension to things.
And also it's about HOW you do the moves -- if you're finding them easy, work on perfect form, even exaggerated form -- go super-deep in lunges & squats, with full range of motion. Bring your knees up above your waist in high knees & up & overs and mountain climbers. Go at the pace of the folks in the video. In other words, dig deep
One thing that might work well for a recent Insanity graduate is to do only the last 2 or 3 weeks of Alpha, so that you can learn the moves & the flow of the workouts (and find out how easy/difficult it is), and then dive right into Beta.
I think I'm getting more out of T25 than I did Insanity, personally, although I did Insanity a long time ago in terms of my fitness journey (right after Power90 last year). And I think the workouts are better-designed, more efficient and represent more "modern" thinking in terms of fitness than Insanity does.