The sole downside to GV is that it'll cost you $20 to port the number in, though the cheapest of cheap cell providers also aren't free.
Otherwise, it's probably the best place to park a number. While they have it, you can forward it all over the place plus make VoIP calls and SMS/MMS with Hangouts on the web, Android or iOS.
If/when you want the number back out, it's free if you paid to port it in. I ported my number to GV years ago and just left it there. I couldn't even tell you my actual cell number without looking it up.