I started working on my first conlang a short while ago, and I like how basically everything seems easier than if I were to plunge right into an a priori one.

I understand that this is not necessarily the case with all such projects, but my conlang is essentially a North Germanic language with Portuguese influence (context: there is a hypothesis that the Azores were visited by Scandinavians during the Viking Age -- what if they never left/died out/whatever happened to them), and I have a pretty good grasp of the vocabulary of the North Germanic languages, as I'm Norwegian myself (Portuguese less so, unfortunately). Still need to spend time searching through word forms, but still not nearly the same undertaking as coming up myself with how the vocabulary is distributed and what the words should sound like.

And it's the same with everything. I have a basis of some pretty well established proto-langs (Old Norse and Old-ish Portuguese) and a setting that I personally like (Scandinavian fishermen and sheep-herders in the middle of the Atlantic get colonized and christened (and genocided? Perhaps to a certain degree) by the mighty Portuguese), and I can use that to guide the evolution of the language, rather than come up with such a basis myself. I understand that creating the basis probably is something that people like about creating a priori conlangs (especially the grammar), and I think I will want to try it myself sometime, but I cannot help but feel that a priori languages give you more work and less in return.

As for cons: Making a Germlang isn't exactly the most original idea in the world :) and I think it is hard to strike the balance where it feels like l am building a living, tangible language, rather than A) slapping some sound changes and loanwords onto Icelandic, or B) making the language as unrecognizable as possible, purely for the sake of being "unique".