Before I begin, though, the context is that I had never had a tablet before. I can't compare it to an iPad or Android tablets.
- Performance: the first and foremost issue with Surface is with its performance. I've been using it to browse the web and mostly to read email/news on sites like Gmail and Google Reader. The perceived performance is bad for things like: click/touch to open a new table, time to launch/render web sites (as compared to other computers on the same network), time for the typed characters to show up on the screen (you probably saw reports that Microsoft Word did not keep up with the user typing a document and it's no different for me on sites like Gmail). I tried other applications, mostly Kindle, and its rendering time is bearable, but I expected more (especially as you compare it to smartphones that have much better perceived performance). And, as a last example, rotating the screen from landscape to portrait mode is quite slow in my opinion.
- Multi-tasking: as Windows 8 doesn't have that many applications (in my case, especially a good Gmail client), one needs to use Internet Explorer to launch the web versions to be able to accomplish one's tasks. If you want to launch something to keep running in the background, like an internet radio or YouTube, you should try for yourself to switch away for IE metro version. It stops running! But the irony is that, if you go to the Desktop and launch its IE version, it keeps running in the background as you switch away to Metro apps.
- Touch interface: I don't know if the problem is with my inexperience with touch interfaces, but it doesn't respond as well as I'd expect. I find myself having to touch it multiple times to get something done. Sometimes it confuses a touch with press-and-hold and selects the text or shows up some option. I confess I lose patience with this touch interface.
- Keyboard: I have one of those Surface touch keyboards. My productivity with it, combined with all the performance problems I mention above, is way low compared to an actual keyboard. And note, I do touch typing on any keyboard, but even after 4 weeks I couldn't get used to the touch keyboard. I plug my regular keyboard into Surface to be able to reply to emails or write any longer texts.
- Desktop/Metro mix: enough has been said about Windows 8 inconsistencies, but I have to say that they do bother me. Just two examples: (1) you connect your Bluetooth headset to the Surface and do partially through the Metro UI, but in order to really know and troubleshoot if it's connected, you need to go back to the desktop and launch the control panel; (2) I wanted to prevent Surface from sleeping automatically when it's charging, so I could continue to listen to music, and in order to do that, you need to go back to the control panel and find the options with your keyboard and mouse, just like any regular Windows 8 device. Not to mention that touching on the help options in the Metro UI sometimes takes you back to a help dialog on the desktop.
- IE lack of configuration options: IE Metro and Desktop have different configuration options. If you want to change your search provider, for instance, or set a proxy or even see the source code (as I was troubleshooting an issue), you can't do any of these things in the Metro version - but you can in the desktop version. Not only that, but I'd love to have Microsoft allowing other browsers on Surface, as oftentimes some sites don't work well with one browser, but work well with another. In terms of features, IE doesn't seem to be the only one, as Skype (Metro) is also a stripped down version of the desktop version.
After this experience with Surface, I went back to an old laptop (5.5+ years old, also running Win 8) and I was absolutely amazed at how the old laptop was blazing fast compared to Surface. And we're talking about a laptop with a mechanical hard disk, as compared to Surface with a flash drive. The performance must be definitely improved so I can justify the Surface cost. At this point, it's a better to purchase a low end laptop, as it will give a better performance.