Wow - what a broad question. By defects I think you mean disadvantages - but that is relative to other cards, and of course their are going to be other cards that are better and faster, and ones that cost more and cost less.
If you want to find the best card for your system, you need to post full system specs - make and model for all major components - and identify the games you play, at what settings and monitor resolutions, and what you budget as.
Alterrnatively, this site has a page to help you identify system requirements relative to upgrading your video card and your preferences:
You could go with a faster video card if budget allows. While it might start to be constrained by other parts of the system, depending on the game, it could still improve FPS by a fair amount for some games.
You still need to confirm that your PSU is large enough for the option you select.
When you can, you should also to increase the amount of memory you have. What operating system are you using and is it 64 or 32 bit?
Dont worry about all the metrics. Those numbers individually are not signficant as performance depends more on how they all work together, with the architecture of the card, with the particular games, game settings, and monitor resolution.
Better approach is to first define your system requirements and personal goals, as explained in more detail here (same site linked above):