I've collected and played a fair deal, and honestly it's not too bad as far as CCGs go.
As far as user friendliness, it is extremely user friendly. I spent 8 hours as ConQuest helping people learn the game, and after just one lesson and a few practice games with just a BattlePack and a starter, most players were very comfortable with the rules. The system is even easier to pick up for those who have played the MMO.
As to impressions, it's hard for me to place where it stands exactly. It's not nearly as initially difficult to create a competetive deck as, say, L5R can be. It can be frustrating (as someone pointed out) to collect only certain primary/secondary sets. However, if one just wants to play some, a few battlepacks/boosters is a really good time.
There are also certain rare cards that might be nearly universally handy to have (not nearly lotus/mox or GnF/AFV level), which might be a bit hard to come by. Then again, a lot of those cards are only to add that final punch to a collection, and in no way are necessary for having some fun.
The game can also feel somewhat barren at times, with certain power sets listed but not yet released. This won't hinder the game as is, but if you want Earth Control, for instance, you won't find it yet. That being said, there's a lot to look forward to.
Of course, you can play your own heroic creations with the hero card generator AEG has.
Someone else mentioned multiplayer play, and it's true. The game is really fun in a team game, 2v2 or 3v3. Going bigger than that can result sometimes in the last person to take an action (it goes back and forth between the teams) being knocked out before his turn actually comes up. But 2v2, it can be a real crazy time.
The game can sometimes lend itself to rock-paper-scissors syndrome. That is, if you play a controller and some tank gets their mez resistance/toggle-knock-off resistance power out quickly, it can lead to a short game. Of course, there are also ways to counter that though.
In all honesty, the most fun my friends and I have had with the game was playing draft (2 battlepacks and 2 booster packs). The decks weren't pretty or well constructed, we didn't have ideal heroes or sidekicks, and whoever drafted a rare power for one of their heroes was lucky. But, it was a lot of fun, with games being well matched and fun.
Overall, I say that it is worth a small initial investment to try it out. If you try the draft, each person should take the hero-specific portions of their battlepacks aside before they begin drafting, and they must choose one of those two as their starting hero. I suggest deck size for the draft around 30-35 cards (we found 35 worked well for us, but that can be up to each playgroup really), with no max similar card limit.
Good luck!
