IE 4 and 5 were innovative (IMO as someone who used both at the time - 1998-2000 - and actively converted family members to IE) compared to Netscape: it had a cache which worked consistently (important in 28.8 modem times) - Netscape would ignore the cache in some situations, i.e. resize the browser window and it would re-download images, even though it had them in its cache, and also IE had things like smooth scrolling which helped make things "nicer" to scroll and feel better from a UI perspective, and things like "make favourites available offline" feature, where it would download a bunch of full pages (whilst you were dialed up), and you could browse them after you disconnected.

After IE 6, things when downhill fast with the stagnation, but before that point, IE was a good browser.