If your stuff feels iffy and has less-than-ideal engineering practices, the slow and steady launch might work great. Expose enough of your idea to keep people idling around and begin free beta testing.
This isn't bad, per se. Everything is a trade off, and if engineering skill or time is not something you have an excess of, the slow and gradual launch can work.
On the other hand, if you have experience building and scaling and are confident that: a) the core of your idea is apparent in your product, and b) you did enough testing that things won't break on launch, by all means, build the hype and open the flood gates on launch day.