MotoGP heads into its 2011 summer break with riders, teams and fans taking the opportunity to look back on the first half of a season that is turning out to be thrilling, intriguing and controversial in equal measures.

With pre-season patter focusing on Valentino Rossi's switch to Ducati and Casey Stoner defecting to Honda, there were plenty of unknowns heading into the opening rounds.

Now, at the half-way stage the two arch-rivals remain a talking-point - albeit for different reasons - with Rossi struggling to find his feet on the Desmosedici, while Stoner is edging away in his quest for a second world title.

But we want to know what you think... We have lined up several riders who we think have gone above and beyond in 2011, whether it's their outright performances (Stoner), their flashes of remarkable speed (Simoncelli), their efforts on lesser machinery (Abraham), or their ability to keep working away in the face of adversity (Pedrosa)

Who has impressed you the most though? To cast your vote, simply CLICK HERE

If you need some help deciding, we outline some of the nominees below...

Starting at the top, Stoner has been impressive this season, gelling well with a Honda RC212V that appears to have made a significant step forward this year, the Australian winning five races and finishing off the podium just once (when he was impacted by Rossi at Valencia).

Rossi, on the other hand, has found the going tough with Ducati, the Doctor's magic seemingly unable to work on the current iteration of the GP11 - or even the rush-released GP11.1. Qualifying has been a particular bugbear, but Rossi's racing nous has shown itself on occasion this season, while he is one of just two riders (the other being his team-mate Nicky Hayden) to finish every race inside the top ten this year.

It is also worth pointing out that Rossi is just 11 points shy of Stoner's tally with Ducati at this point last season - but is that enough to say you are impressed with his performance?

Beyond Stoner and Rossi, Jorge Lorenzo has shown on occasion exactly why he was the runaway 2010 champion, the Spaniard winning twice on a bike that is generally considered to be down on pace compared to Honda this season.

Special mention must then go to Dani Pedrosa, who can only think of 'what could have been' had he not been forced to miss three races due to injury. Capable of matching Stoner on a level playing field, Pedrosa has won two of the six races he has started, despite spending much of his year injured, or recovering from surgery.

On the flip side, Marco Simoncelli - the man responsible for the crash that injured Pedrosa - has been a persistent headline-grabber in 2011, though at times for the wrong reasons. His raw pace, when compared to his rookie season, is certainly impressive, but his inconsistency - and crashes - are conspiring to hurt his reputation.

Of course, you don't have to be a race winner to be impressive at MotoGP level. Colin Edwards scored a remarkable podium in the rain at Silverstone just a week after breaking his collarbone, while Hiroshi Aoyama - though in the shadow of Simoncelli - is top ten overall and has a better race finish than his high-profile team-mate.

Karel Abraham also deserves special mention, the inexperience Czech rider shrugging off his minnow status to establish himself as a consistent mid-field contender, regularly out-pacing the better funded Pramac team.

He is also faring better than fellow rookie Cal Crutchlow, who despite struggling with injury recently, has shown promising flashes of pace, particularly in qualifying. Finally, we have also offered a nomination to Alvaro Bautista, who has overcome his own injury concerns to keep plugging away aboard the sole remaining Rizla Suzuki.

But who has impressed you in MotoGP 2011 so far? In consideration of their machinery and capabilities, which rider has gone above and beyond in 2011...?