Well, Maik, Bryan - what a topic to kick off!
There's been a very interesting discussion this year about it on the
WordReference Forum for Greek which I keep meaning to contribute to. Perhaps I'll post the link Maik found.
Anything Bryan or I say should be ignored by normal people. (Sorry Bryan !!

) We both have backgrounds in learning languages at university which only a relatively few people have. Also I guess we both enjoy the the twists and turns of grammar and complexities of the vocabulary almost for their own sake. In Bryan's case the language is central to his life and his work! So very much μπράβο to Bryan for what you've achieved.
However I do think Bryan is right in what he says about Greek being easy to learn - but only at the beginning. I think anyone should try - a good up to date phrasebook is the best bet. Helps with the (mostly) fairly straightforward pronunciation and introduces you to the alphabet gently with a"greeklish" version alongside. You can choose the bits that suit you best - taverna, accommodation etc. Greeks really do appreciate the effort and even seem a little surprised. I was actually very strongly thanked by an older resident in Katelios a few years ago. You can stay roughly at this level and increase your vocab year by year, without needing lessons which are hard to find outside biggish cities, or even possibly buy a book with a CD. There is some free stuff on the net too. It feels quite good to be able to order a whole meal in Greek for example. The only tricky bit initially is that words can be emphasized in to us "funny places" including on the last syllable e.g. KefaloniA, KateliOS.
But once you want to go into more detailed discussions or topics away from the standard tourist fare life gets very much more challenging. Greek has phenomenally difficult grammar and Greeks tell me they are amazed that a foreigner would want to learn it. They apologise for Greek Grammar in the way we apologise (rightly) for English spelling. Greeks who went to school before 1973 had to learn an even more difficult version. The second difficulty is that this older so-called "pure" version of the language hangs like a cloud over modern Greek. Greeks are very sensitive about the formality/informality of the language they speak. Many words are considered old fashioned and formal but are still used in some contexts, but are completely wrong in most speech, though infuriatingly quite a few are still OK! And vice versa, er so to speak!! Don't make my mistake of trying to read a Greek newspaper too soon in learning Greek - it will be full of words you won't hear spoken! You could try a
light magazine which seem to be much more like what Greeks actually say. This situation changes all the time with new words being created and the language simplifying.
I enjoy all this and I know enough of Bryan here to reckon he does too. As a retirement project Greek is a great challenge and interest that I can heartily recommend. And it will help you get into less tourist areas and experience more of the real Greek culture. I've been remarkably lucky in finding a fantastic teacher very locally.
A final tip: Like we talk about the weather, Greeks love talking about food and cooking - and it's an essential part of Greek life and festivities - especially women but men too. If you can ask a Greek about what they like to eat/cook/what their mother makes you'll very quickly get a friend!
Thanks for starting this Maik!
tony