Since I watch so little TV, I am not familiar with any of the named actors, so have no opinion either way.
When I eventually get to see the series (If RTE buy it or I get to the cinema or see it on DVD), I will probably spend the time commenting "That wasn't in the book" or "They've changed that".
I watch a lot of drama on TV and that's part of the fun for me - seeing someone else's take on a favourite book or play. I'm sure it will be very good, especially with the cast they've got on board for it.
I hope you do get to see it, and I'm sure you won't be disappointed!