I'm in my first grow and using MiracleGro fortified potting soil because I "didn't know any better"...
I actually did get some nute burn early, but the plants worked their way out of it and look great now. In fact, the two that don't look so great are the ones I transplanted out of the MG soil 'cause of the nute burn. I left the other "burned" one in its original pot, and it's looking great.
So, just be careful about overwatering. Get a moisture meter if you're new to growing, and don't argue with what it tells you. For pre-fertilized soil mixes like MG, the key thing is to NOT overwater -- watering these soils releases the nutrients, which little seedlings can't use right away. And, if they do burn, just plug on -- they'll probably pull out of it.