Now Ive got one and am more familiar with how it works I should update on this.
I absolutely love my new toy and over the past month Ive found it to be more capable than I first thought. It's extremely easy to use for daily things such as reminders, news, shopping lists and even just asking it general knowledge type questions.
To answer my own question above. Their 'free' music service via prime covers most of my albums and favourite artists. There's only been a couple of the more obscure or less well known bands -such as Jack's Mannequin which isn't on the free list, but it did play many of the songs by Andrew McMahon (who was their lead singer).
If you do have favourites that arent available for free, you have a couple of options:-
1) You can pair your mobile phone/tablet and play music from there
2) You can upload 250 songs from your PC to your free 'My Music' account.
This means for me its not been a problem and I'm more than happy with the included service. It will also play 'Music Stations' which offers a wide variety of choices and tastes in music. If you want all the latest hits and releases though I should imagine you may find those only on the payfor lists.
Alexa learns quite quickly and Ive found the voice recognition better than Google/SVoice/Siri and very intuitive. I can just say things talking normally and without any emphasis. My friend & I had some giggles the other day - She has a wolves accent and it had previously only been used to my voice.
The free IPTV is OK. It does offer a selection of newish movies. IMHO its never going to beat Netflix, but then again its unfair to compare free -v- a payfor service. You can upgrade but I haven't as I don't really watch that many films and there is enough in the free section to keep me going for a while if I do get bored.
I also get access to quite a large library of free iBooks but you can pay more for access to a full library.
For those of you on here who tested the TP-link smart plug - it works with that - Much easier to say "Alexa turn on blah" rather than using the TP-link app.
I'm still learning and haven't yet explored all the Alexa Skills as there's thousands of them to choose from.
IMHO best geeky thing Ive bought for a while and if you took it away from me now I really would miss it.