Allow me to add to what David has written regarding the Modern UI.
Much has been maligned about a missing start icon. Indeed as David has implied, it is not missing. The idea being, as he indicates that the Start icon (Bottom-Left Corner) take one to the Start screen & Tiles. It is true this/that screen can be used OR NOT... completely optional. So, as he points out is what Tiles it has on it, their size & grouping.
As too the value of certain APPs that to is subjective. But, whether those applications, any of them are accessed via the Moder UI Start screen & via Tiles OR NOT is, also, optional. To explain:
When one 1st boots into Windows8 Tiles can be hit; then Open/Active items will sit on the Switcher Bar or what I have been calling the APP Bar. Now control gets really nice from that location. Things like Calendar, Weather lie 'in waiting, can be Close (from) there or Snapped to be viewed & share the screen along w/ other things. OR one can go directly to Desktop & then, from there select any desired application in a few ways... by going back (& forth) to Start ( but, that's unnecessary); by going to WinQ & back to Desktop OR by having the (all) applications in a folder on the Taskbar (see photo), this being my preferred method as it allows never leaving Desktop. Yes, the idea is that the Start icon takes one to a 'graphical' display of start menu items. Frankly I find that more trouble than it's worth.
But, the take-away here is the incredible versatility of Windows8. No one is forced to use the Modern UI or the Start screen & Tiles, though it can work nicely for some people, some people will come to like using that & doing things w/ it. Some/ many, like myself are happier working on, in & from Desktop.
Yes, great value can come from using the so-called Power Users menu (Rt Clk Bottom-Left Corner); another helpful tip is to enable the Desktop Toolbar (Rt Clk Taskbar > Toolbars & select Desktop... the neat thing about this is any shortcut or other Desktop icon shows (here) even if you uncheck "Show Desktop Icons" & thereby have nothing on top of pretty wallpapers. Links is another handy one to enable as items there equate Favorites Bar content... Favorites Bar can be hidden & yet via Links can go to a site even w/out having a browser open 1st. Some Keyboard shortcuts are really worth learning & using, too... WinE is an example but, there are many.... I listed them in this forum somewhere in Tutorials, long ago.
At the end of the day (hate that expression, lol) Windows8 can be so fast & easy to find things, access things, navigate that it is, in a way, actually fun to use. Things can be quicker, more efficient, more @ your fingertips & direct than, even, Windows7 & certainly moreso than that old start menu thing was or allowed.
Once you get hip to using the APP Bar in conjunction w/ Desktop it gets damn cool. I tried lots of add-ins & retro-fits...all unneeded! Windows8 works beautifully 'as is', right out of the box. As David & I are point to it can be a personal hybrid of it's Features & abilities as you discover what's available & possible & how all they forms your particular 'comfort zone'. Many APPs are useful, some are silly & some, true enough have & have always had similar more conventionally accessible alliterations that are web-based.
Oh, BTW, @ boot, you can go to Desktop 3 ways:
1. Clk Desktop Tile
3. Put the Desktop Tile as Top-Left most & hit Enter... whatever Tile is in that position, upon hitting Enter, that's where you will go.
Actually there's a 4th.... if say something like Outlook or WL Messenger is a Tile, hit that & it will open on the Desktop.
Here's the promised photo. You just scroll up/down & click on the application wanted. This or WinQ means you can actually have no Tiles on Start except Desktop, if you wanted. Myself, I think having everything on Start as Tiles & scrolling looking for a Tile is ridiculous but, each to their own. If you are going to use Start & Tiles, tailor it so no scrolling is needed.
This doesn't exist, by default but, it's easy to create. I put the instructions in the forum, already, also. Be glad to tell anyone how or point you to the instructions. Myself, I really like this 1.
As for the technical goodies under the covers & what you consciously or unconsciously gain from them in Windows8... that's huge... for both End Users & certainly for Enterprise.
Oh & although there are several ways to get to things & Search... it is kinda neat how you can begin typing in the middle of nowhere on Start & whoosh it goes to the sought item & way before you finish typing, lol.
Lastly, never think the lack of a touch-screen impedes the Windows8 experience... it does not, @ all!