I've used lovefilm for about 3 years now, always found it to be very good, the trick with TV series' is to only ever have one on your list at any one time, they'll send the DVD's in box sets out in the right order, but if you've got for example CSI season 8 part 1 and part 2 on there they may send part 2 first if it's in stock as it's a different item as far as their system's concerned.
Films wise my account says I've had over 250 from them, no blu-ray player yet, but I'm sure the more recent releases will be well stocked in both formats.
Plus if you rent something and it turns out to be rubbish, I don't feel bad about stopping it, and sending it back unlike if i'd rented from a shop or bought it.