R50A UMPC (Ultra-Mobile PC) of ASUS has been kind of lost in the company's flood of "Eee PCs". Possibly for good reason, the crew at UMPC Portal just reviewed the 2,000 dollar hand-held and came away unimpressed.
overall the software package was characterized as "atrocious". In addition, the lack of a keyboard was annoying. The biggest problems were all generally related to running Vista on the 1.33GHz Atom Z520 CPU with 1GB RAM. Bloat-ware can be deleted and a bigger stylus can be used. But "pretty bad" performance on the lowest possible graphics settings can't be fixed.
Initial reports seemed vaguely promising, but Ben over at UMPC Portal has found things less impressive. Chief criticism; aside from the bloat-ware, cramped writing area and difficult form-factor – is the sluggish performance. Otherwise it's the expected drawbacks of pricing and keyboard absence that really damage the R50a.
An existing R50a owner has already replied to the comments with his own experience of the UMPC. Contrasting significantly to Ben's experience, Arthur was satisfied with his performance of the R50a. He said it can play back iTunes video and Slingbox stream video without skipping. In addition he said that it can play the graphics and game graphics. Vista performance scores were both higher than those on the UMPC Portal review unit.
He said his overall Vista score is 2.7. His Graphics score is 2.9 and his Gaming Graphics score is also 2.9. 
The other Vista scores are the same as of Ben. He also said that his unit did not come with any bloat-ware. Arthur does not use the security software. Therefore, he does not get the popups. He said this is the first UMPC he has owned which can playback Itunes video and Sligbox video without skipping.
Arthur added he loves the device and finds it responsive. He also said that it has great battery life, the fan is quite (unlike his OQO 02) and it is small, although not pocketable. He wishes however that the mouse pointer worked better and that it had a keyboard.
Resources:
User's positive opinion about ASUS R50a
User speaking negatively about ASUS R50a
Review of ASUS R50a UMPC: Problems related to running Windows Vista