The development of Talk Talk from their first album to their last is the most incredible development of any band ever, I think. The first album isn't particularly strong. It has the odd nice song (I'm fond of the Talk Talk song actually) and Mark's voice of course, but the sound is bad bad synthipop. It's hard to imagine anything more different to the sound and production of Spirit of Eden and Laughing Stock than actually Talk Talk's first album.
It's My Life still sounded quite thin and cheesy but already had several examples of amazing songwriting. Actually there's a very nice single "My Foolish Friend", which appeared, I think, a bit later than the first album; this made me aware of them at the time and is the first example of their songwriting competence. Nothing "proggy" but very enjoyable pop music.
The first thing that really blew me away was watching them live, particularly the version of "Call in the Nightboy", on the tour on which the Montreux CD was recorded. I think it's also on youtube. On that tour, they improved their sound and dynamics big time, despite playing the same songs as before.
"Colour of Spring" then is their first truly excellent album with top notch catchy songs, wonderfully warm and deep sound, and some clear experimental/prog elements.
Spirit of Eden and Laughing Stock are then just a league on their own.
Mark Hollis' solo album, by the way, is also great, as are the two .O.rang albums. Pity that both these acts growing out of Talk Talk have ceded to produce stuff.
By the way, Talk Talk are actually very strongly appreciated and pretty well known also outside the Prog world. The really stunning band that nobody knows is .O.rang - check them out! (It seems difficult to get hold of their first CD "Herd of Instinct" which I think is the better one - actually 5 star material in my books.)
Did I mention that I'm a big fan?