Piper Tomahawks were intended to stall properly and spin aggressively. As a student PPL on the Tomahawk I can confirm that the stall can be moderately alarming. Certainly far more so than on the PA28.
The controversy is due to whether some Tomahawks don't exit the spin as readily as they should. There's a story (that I don't know quite whether to believe) that production Tomahawks differed from the prototype and have less rigid wings. Some apparently spin more predictably than others.
I've never spun a Tomahawk, but both my instructors have. One says 'never again' whilst I think the other would rather enjoy the experience. Unfortunately, Tommies aren't certified for intentional spins any more.