Ultrabook is an Intel trademark, and the line between laptop/notebook and ultrabook has blurred. There are a variety of form factors and features for each personal computer now.
It is absolutely true that "U" suffix is an ultra-low voltage CPU running at lower power to conserve battery life and that not only are the number of cores and clock speed being factors, the construction of the CPU itself is a speed/performance factor and there's a base clock speed and often a turbo speed that the CPU runs faster when it has to do so.
As very few CPUs or laptop graphics can be upgraded, very simply look at the rated CPU performance as one of the factors among all the specifications when purchasing a laptop. You can consider brand name and the sub-brand (like Envy vs Pavilion, or Essentials Lenovo G series vs their better Ideapads or better again Thinkpads). You can look at whether the battery is user removed from the outside or encased within the laptop and not able to buy a spare or replacement easily. You consider graphics processor if using it for gaming or heavy graphics software needs. You can consider the ethernet speed when plugged in by a cord for streaming and downloading large files where gigabit 10/100/1000 is faster than FAST which is 10/100. You consider size and weight and the battery mAH or Watt-hours and try to convert to see battery power. You look at everything available to compare one to another to decide on the best value for your money.
For CPU speed, choose a table of reporting:
http://www.cpubenchmark.net/...u_list.php
http://www.notebookcheck.net/...436.0.html
Do not worry about the cost of the processor because it is generally now soldered to the motherboard and can't be replaced. If it cost $200 or $30, what does that matter? It is the total laptop price to consider.
Ultrabooks as a trademark name are laptops, but the newest ones have special convertible features and are particularly light in weight for their class and do have good battery life. They only can have an Intel CPU (rather than AMD). Intel decides how well the design and features compare to a MacBook, and if it is a clear competitor to a Macbook, they can allow the name to be used on it. That is not shown anyway, but has been the criteria.
Here is the latest Rescuecom report:
http://www.rescuecom.com/...14-q3.aspx
They are a USA based large service company and they publish the number of laptops needing repair versus the laptop market share and convert to a score.
Raw data is here:
http://www.rescuecom.com/...#more-8411
Note that Macbooks are very expensive for their performance and run OSx, and Samsung no longer sells many laptops, having discontinued all lower priced standard laptops. History shows Acer, Dell, and HP for the last year or two have fallen to similar reliability quarter by quarter and can now be considered "generic" along with Lenovo G series competing with them. Low priced Toshiba Satellite and Asus seem to be in the same bunch of low quality in general. This information is based on the questions I have answered over the last three years in Y/A, my background history, rescuecom data reports, and other historical reports and does not say you can't have issues with any laptop.
