Been a while since I started this thread!
I'm still watching the show. I'm now up to the last three episodes of series 4. I'm going to my brother's house to watch them this weekend. He and his wife are huge into Doctor Who and my sister-in-law insists on watching specific episodes with me. I don't mind at all. I love being able to watch the show with other fans and discuss it afterwards. The waiting between episodes, however, is killing me!

If I was going at my own pace I'd probably be caught up by this point.
Because I absolutely LOVE this show! It feels exactly the same as when I was getting into Star Trek for the first time almost 20 years ago. I'm glad that the show is very episodic, with the exception of 2-parters and the small little bits that are built up throughout the season (i.e. Bad Wolf, Torchwood) because I never know where the Doctor and his companion will end up next. Just like Star Trek, there is a new adventure every week.
I loved Christopher Eccleston's portrayal and I wish he had done at least one more season. It's hard to compare him and David Tennant, as Tennant was on the show for much longer, but they both have their strengths. Eccleston did an awesome job portraying the Doctor's serious side, while Tennant is always good for a laugh. I'll be getting my first taste of Matt Smith very soon. I don't know what to expect from him at this point.
I was very sad to see Rose leave the show, but I was satisfied with where they left her, being with both of her parents (even though it wasn't technically her dad) and Mickey. Rose has shown up in brief, blink-and-you'll-miss-them moments in season four, so I'm assuming that it's leading up to something.
Martha Jones had very big shoes to fill, but I ended up liking her. But for me, Donna Noble is second after Rose. Catherine Tate is so funny! I knew her from the office and had no idea she was on Doctor Who! The episode that reintroduces her, "Partners In Crime" had me in stitches when the Doctor and Donna see each other from across the room. They're both mouthing words to each other and Donna is using facial and hand gestures throughout the whole thing while the people that they're spying on are just staring at them!
Standout episodes from each season for me include:
Series 1: "Father's Day" "The Empty Child"/"The Doctor Dances"
Series 2: "School Reunion" "The Girl in the Fireplace" "The Impossible Planet"/"The Satan Pit" "Army of Ghosts"/"Doomsday"
Series 3: "The Shakespeare Code" "Human Nature"/"Family of Blood" "Blink"
I'm hoping to keep this thread going so I can discuss some of these episodes some more.