So I just got a friend of mine into the game and was showing him around. He quickly latched onto the engineer as he enjoyed the tech based classes in other games and the turret style of builds. I had mentioned to him that Turrets were not that good and he shrugged. Shortly after that we decided to do a dungeon which quickly showed him just how flawed the turrets were and his heart sunk. His interest in the class vanished and I felt so bad. I wanted him to enjoy himself but all he got was disappointment.
A viable Turret build has been something I've been wanting for a while too. I love these sort of summon/pet/totem builds and engineer's should be viable. But it just isn't. I personally have a few ideas on how this could be fixed but the consensuses on the forms usually seems to be that any sort of pet build should never be viable because of PvP. I've always hated this response since it stripped a vital play style specific groups of players enjoy and my response to that is always if its overwhelming arena net needs to just make it work regardless. My friend might still play the game but without a main class that he clicks with he is likely to just quit, which I've seen countless times.
One option I'd suggest is to scale the Turrets based on the player's stats. Another is to use the charge system with the turrets so the player doesn't have to pick them up constantly and perhaps allow them to have a couple of a single type. I'd also like to see the turrets unified with the tool belt skills with their turrets so their abilities directly influence the turrets in some way. One example I'd use would be be that thumper turret still has rumble that breaks you out of stun but also does a shockwave around all your turrets, damaging foes and or providing stability for allies. Or perhaps Rocket turret shoots a flurry of rockets based on the number of active turrets you have. These are just examples and not actually suggestions. Lastly I personally think turrets should be thrown on summon rather than set on the ground to promote a more active gameplay with them. Since that's part of what I'd like to do with them. I wouldn't mind and I doubt new players would either if turrets total duration before they disappear. Sure this removes people's AFK farming builds, but honestly that's not a major loss compared to the advantages we could be seeing.