Are SharkBite plumbing connectors as reliable as soldered connectors?
So far they seem to be just as reliable, although given that they've only been on the market for a few years they don't have the same history as soldered connections. Here in the UK almost all new-build houses use push-fit connectors for concealed work as it's much quicker and easier.

You most likely do need to take extra care that the tube is perfectly round for an inch or so at the end, and that there's no bits of swarf, paint or other dirt there. Solder is good at filling in little gaps which push-fit connectors won't seal. On the other hand it's very easy to not heat a solder joint up enough to melt the solder properly, especially in confined spaces.

Obviously, make sure you push them in firmly.

Finally you don't really want to use them for exposed pipes, soldered joints are much neater.