I've played GW games up until 8th edition Fantasy was released a couple of years ago, quit 40K well before that (during 3rd edition).
Awesome miniatures and background, crappy rules and business model.
5th edition of 40k is out, seems a lot more balanced than what little of 4th I've seen, as for GW's business model, what is putting you off about it?
Pricing would be the first.. they do produce great models but their price model is insane, i.e. far too costly.
In that vein one also has to mention that they adapt the rules to need more miniatures either by lowering the points costs of models between editions so you will have to need more of them to play competitively (very evident in the switch from 7th to 8th edition where you basically needed to double your infantry model count or esle you wouldn't take full advantage of the new rules).
Rules are sometimes very imbalanced.. units exist that utterly dominate the battlefield because they are either too powerful or too cheap, sometimes both (i'm not familiar with current powerbuilds but the Imperial Valkyrie swarm was something that could easily mop the floor with opponents if they didn't play heavy anti-air which almost never happens).
It has become too expensive to start a GW hobby.. if one is to play a standard 2000 points Fantasy or 1500 -1750 points 40K game one needs to invest at the minimum 300$ (and that will likely be a low model count, super elite army) to get it on the table and then you don't have much variation possibilities and are possibly missing some units. When you compare that with other companies you get way more than you need for half of these costs.
No veteran gaming support - once you are an established customer you no longer seem to matter to GW. There is Apocalypse but honestly who plays that on a regular basis? If you play Superheavies or even Titans you either mop the floor with the opponent who didn't bring their own or the game will be decided which ones get destroyed first.. dice rolling with a bucked is not gaming to me.
Specialist Games have long ago been disbanded bit they contained some of the most awesome games GW has ever published, e.g. Blood Bowl, Gothic, Mortheim. They may not produce the revenue desired by GW (or whatever was the reason they buried them) but they are the perfect way to introduce gamers to GW.. low model count so rather low monetary investment, good game design and a good introduction to the GW background. More than one player i know started off with these games and then switched over to one of the main games.
So yeah.. GW is shooting themselves slowly in the foot by pricing themselves out of their customers reach and then they piss off the veterans by designing crappy rules that are imbalanced and easy to exploit for powergaming purposes. Their newest company reports show this by losing nearly 25% value and the closing of many stores and HQs around the world (they closed the main office of GW Germany last year). Problem is that they now have heavy competition with other gaming companies that offer a wide variety of backgrounds from historical to Fantasy/SF and their prices are more on the sane level (sometimes because they require less models sometimes because they are cheaper) so people have started to jump ship or never started with GW to begin with.
So anyway.. rant over