Squier Bullet Stratocasters are designed to be affordable, entry-level instruments and they are very good at being exactly that. In my opinion, if you can afford to move up to the Squier Affinity Stratocaster, you’ll get a better all-around guitar, but there is absolutely nothing wrong with playing a Bullet Strat when you are first starting out.
If you intend to play hard rock and heavy metal you’d be wise to get a Bullet Stratocaster with an HSS pickup configuration. This means it has one humbucker and two single-coil pickups. The basic Strat design features three single-coil pickups (SSS), and that’s fine for rock, blues, and country. However, a humbucker will sound better for metal and hard rock.
Most Bullet Stratocasters also have “hardtail” bridges. This is different from the tremolo bridge found on traditional Stratocasters (even Squiers). For beginners, it means slightly better tuning stability and less aggravation.
Again, I usually recommend Squier Affinity Stratocasters for beginners, and if you are into metal, there is an HSS model. However, if you are really counting your pennies, there is nothing wrong with a Bullet Stratocaster. Many new guitarists get their start every year with a Bullet Strat, and it has remained a popular guitar for a good reason.
Remember, this is just my opinion. Always do your own research before choosing gear!