Not as bad as some make out to be. Certainly no masterpiece, but it is interesting. Really bad accents at times, but if that kind of detail doesn't distract you then any liberties with historical accuracy aren't likely to either.
The subject does whet ones appetite for a really good biopic, so perhaps someone will throw some money at it some day, cast more Italians, better sets.
For a low budget attempt at telling a story, it gets the job done, and it does have redeeming moments. If you're interested in the engineering, beyond the "you cannot fit 4 carbs i there!" or "pop-up headlights are too complicated", you'll be left wanting.
If you're happy enough to spend an hour and a half getting a very cursory look at the Lamborghini story, and can overlook some marginal acting, go for it.