In terms of which Irish whiskies are good, that depends on your palete. The biggest selling Irish whisky in Ireland is Powers Gold Label, although outside Ireland it's Jameson. If you're used to Islay Scotch, I'd recommend Conemarra single malt, for when I tried it, my first thought was that I wouldn't be able to differentiate between this and a highland malt in a blind tasting.
If you wanted to try something different, I'd point you in the direction of something uniqely Irish - pure pot still - which uses both malted and unmalted barly. To my knowledge, Scotch (blended) doesn't use unmalted barly. Redbrest and Greenspot are examples of this, and both work over your tastebuds in an interesting fashion. Greenspot doesn't take any prisoners, but is much harder to find. Redbrest (in my neck of the woods) is reasonably priced, and gives that pure pot still character less agressively. Pure Gallus
!!! (I think that's the term.)
Very reasonably priced are Black Bush and Jameson 12, which are sherried, light and great value. I have some issues with the value given by the single malts - the 10yr Bushmills would probably be incredibly booring to a dedicated Islay fan. Other expressions of Bushmills have finishes (16yr in port pipes, and 21 in Madiera casks). Middleton VR is a really good example of top-notch whiskey, buy it's cost makes it's value questionable in my eyes. Conemarra is OK, and I've never tried Lockes or Kilbeggan.
Hope some of this helps
My, but I do like to ramble on sometimes...