Eto'o is a very good player, arguably a top 5 striker but he is nowhere near Henry in terms of overall ability. In terms of finishing they are close. Inside the 6 yard box, Eto'o might even be better, but Henry fits Arsenal a lot better, he creates a ton for his teammates. When healthy he's always among the leaders in assists and in Arsenal's attack they have a lot of moving parts. For example, Henry likes to drop back to the LW to collect the ball and start the attack. Eto'o to me is not as vesatile and Arsenal's attack would probably suffer unless they change the way they play.
The Hargreaves move has been in the makings since last summer. Almost inevitable really.
As far as Parker, that is quite a loss for Newcastle. Rumors are that Allardyce would buy Barton to replace Parker. That would be a downgrade although Barton would come for cheap. It would depend on what they could do with that 8.5. Parker improves West Ham's midfield in a big way.
Ballack actually moved on a free transfer. So that wasn't much of a coup.
As far as Sheva goes, going into this past season I believed that Sheva was one of a handful of strikers that could succeed in any league. Not sure what happend to him this past year in the EPL. Maybe he needed a year of adjustment or perhaps it was the style Chelsea plays.
The difference is United don't need Nani and Anderson to peform in order to repeat as champions. Both these signings, especially the Anderson signing were made with an eye torwards the future.
United had a need for more cover at winger, and Nani is closer to being EPL ready. But they still have Giggs, Ronaldo, and Park. Those are 3 legit wingers as well as the option of playing Rooney in a wide position in a pinch.
The 2 Chelsea signings were made with an eye torwards winning the Champions League. 2 very different situations.
Rooney, C. Ronaldo, Nani and Anderson(if they pan out), is quite a collection of young talent.
ASU is right, both Nani and Anderson has veterans at United to buy them time.
IMO, there is no such thing as being EPL ready for any player who has never played in the league, regardless of how good they look playing in other leagues. Some of them has the ability to adapt right away, and some just takes longer depending on many other factors.