I hope for a good new edition though, but GW has a record of making the odd numbered edition the bad ones.
1st ed - before my time.
2nd ed - great edition but too many rules and add-ons, I think there were like 20 different kind of grenades alone.
3rd ed - buy double the size of an army or don't play, overwatch making both armies sit and wait until the game ends or run forwards and loose. (made me quit)
4th ed - Nice new balance, some streamlining but it was easier to play.
5th ed - CC and troops edition, many add-on books but no codex eldar :|
6th ed - Flyer edition, with shooting as the only way to win a battle, Allies, forts and lots of random stuff thrown in.
Overwatch was in 2nd ed, one of those many rules you mentioned. It was removed in 3rd.
As for their odd numbered editions being bad ones, I have to disagree on that.
3rd edition was the one that laid the ground work for all of the editions to follow. When GW made the change from 2nd to 3rd, it wasn't like current edition changes where they are adjusting a rule here or adding something there. They made a completely different game. The only thing that stayed the same, really, was the name and the models. I was going to say armies, but Rasmus would pipe in about the squats.
From everything I have heard about 2nd, 3rd was a much easier game to play. A lot more streamlined and a hell of a lot less complex. Going from a game taking all day to being able to play with twice as much stuff and getting it done in a couple of hours, where is the bad part in any of that? But as 3rd edition really was the first edition of the way the game plays now, there were some issues that had to be worked out, primarily one model being able to wipe out an entire squad in combat, and the rhino rush. 3rd ed also brought in City Fight.
In 4th ed, rhino rush was gone and they overhauled the combat system so that it wasn't as effective (remember the 2" kill zone). Shooting was given such a boost, especially when they redid Codex: Space Marines and gave Assault Cannons rending. If you weren't playing Assault Cannon spam, you weren't competing. Add in vehicles becoming gun boats and combat armies didn't really stand a chance. Still had the same scenarios that you had in 3rd, just with three different levels of engagement. In addition to redoing the rules for City Fight, they also brought in Apoc to sell bigger toys.
5th ed, toned back shooting, tone back vehicle effectiveness and gave gun boats a real kick in the nuts. Combat was back to being king amphetamine parrot. Fell prey to codex creep in a bad way, if you weren't playing a select few armies, you weren't competitive. Brought in Planet Strike and Spearhead.
6th ed, so much amphetamine parrot was broken that they redid the edition in what, 20 months? How badly written does an edition have to be for GW to say "There is too much stuff to fix that an FAQ will not work, we just need a rewrite"? Granted, as I play a shooting army I have really enjoyed this edition, primarily because my Dark Angels are actually able to make people scratch their head and say "Wow I didn't think that was that strong!" Brought in Escalation and Stronghold Assault.